Transition payload hash option names to hmac

The payload-hash-* options are imprecisely named. Clarify their function
as HMAC validations by renaming them. The existing options will continue
to work but are deprecated.  Log a warning if the old options are used.

All tests, examples, and documentation are updated.

Fixes #289

docs/Hook-Examples.md

@@ -46,7 +46,7 @@ This page is still work in progress. Feel free to contribute!
         {
           "match":
           {
-            "type": "payload-hash-sha1",
+            "type": "payload-hmac-sha1",
             "secret": "mysecret",
             "parameter":
             {
@@ -166,7 +166,7 @@ Values in the request body can be accessed in the command or to the match rule b
         {
           "match":
           {
-            "type": "payload-hash-sha256",
+            "type": "payload-hmac-sha256",
             "secret": "mysecret",
             "parameter":
             {

docs/Hook-Rules.md

@@ -9,9 +9,9 @@
 * [Match](#match)
   * [Match value](#match-value)
   * [Match regex](#match-regex)
-  * [Match payload-hash-sha1](#match-payload-hash-sha1)
-  * [Match payload-hash-sha256](#match-payload-hash-sha256)
-  * [Match payload-hash-sha512](#match-payload-hash-sha512)
+  * [Match payload-hmac-sha1](#match-payload-hmac-sha1)
+  * [Match payload-hmac-sha256](#match-payload-hmac-sha256)
+  * [Match payload-hmac-sha512](#match-payload-hmac-sha512)
   * [Match Whitelisted IP range](#match-whitelisted-ip-range)
   * [Match scalr-signature](#match-scalr-signature)
 
@@ -110,7 +110,7 @@
                 "source": "header",
                 "name": "X-Hub-Signature"
             },
-            "type": "payload-hash-sha1",
+            "type": "payload-hmac-sha1",
             "secret": "mysecret"
         }
     },
@@ -150,9 +150,7 @@
 
 *Please note:* Due to technical reasons, _number_ and _boolean_ values in the _match rule_ must be wrapped around with a pair of quotes.
 
-There are three different match rules:
-
-### 1. Match value
+### Match value
 ```json
 {
   "match":
@@ -168,7 +166,7 @@ There are three different match rules:
 }
 ```
 
-### 2. Match regex
+### Match regex
 For the regex syntax, check out <http://golang.org/pkg/regexp/syntax/>
 ```json
 {
@@ -185,12 +183,13 @@ For the regex syntax, check out <http://golang.org/pkg/regexp/syntax/>
 }
 ```
 
-### 3. Match payload-hash-sha1
+### Match payload-hmac-sha1
+Validate the HMAC of the payload using the SHA1 hash and the given *secret*.
 ```json
 {
   "match":
   {
-    "type": "payload-hash-sha1",
+    "type": "payload-hmac-sha1",
     "secret": "yoursecret",
     "parameter":
     {
@@ -208,12 +207,13 @@ will be tried unless a match is found. For example:
 X-Hub-Signature: sha1=the-first-signature,sha1=the-second-signature
 ```
 
-### 4. Match payload-hash-sha256
+### Match payload-hmac-sha256
+Validate the HMAC of the payload using the SHA256 hash and the given *secret*.
 ```json
 {
   "match":
   {
-    "type": "payload-hash-sha256",
+    "type": "payload-hmac-sha256",
     "secret": "yoursecret",
     "parameter":
     {
@@ -231,12 +231,13 @@ will be tried unless a match is found. For example:
 X-Hub-Signature: sha256=the-first-signature,sha256=the-second-signature
 ```
 
-### 5. Match payload-hash-sha512
+### Match payload-hmac-sha512
+Validate the HMAC of the payload using the SHA512 hash and the given *secret*.
 ```json
 {
   "match":
   {
-    "type": "payload-hash-sha512",
+    "type": "payload-hmac-sha512",
     "secret": "yoursecret",
     "parameter":
     {
@@ -254,7 +255,7 @@ will be tried unless a match is found. For example:
 X-Hub-Signature: sha512=the-first-signature,sha512=the-second-signature
 ```
 
-### 6. Match Whitelisted IP range
+### Match Whitelisted IP range
 
 The IP can be IPv4- or IPv6-formatted, using [CIDR notation](https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing#CIDR_blocks).  To match a single IP address only, use `/32`.
 
@@ -268,7 +269,7 @@ The IP can be IPv4- or IPv6-formatted, using [CIDR notation](https://en.wikipedi
 }
 ```
 
-### 7. Match scalr-signature
+### Match scalr-signature
 
 The trigger rule checks the scalr signature and also checks that the request was signed less than 5 minutes before it was received. 
 A unqiue signing key is generated for each webhook endpoint URL you register in Scalr.

docs/Templates.md

@@ -6,7 +6,7 @@ In additional to the [built-in Go template functions and features][tt], `webhook
 
 ## Example Usage
 
-In the example `hooks.json` file below, the `payload-hash-sha1` matching rule looks up the secret hash from the environment using the `getenv` template function.
+In the example `hooks.json` file below, the `payload-hmac-sha1` matching rule looks up the HMAC secret from the environment using the `getenv` template function.
 Additionally, the result is piped through the built-in Go template function `js` to ensure that the result is a well-formed Javascript/JSON string.
 
 ```
@@ -44,7 +44,7 @@ Additionally, the result is piped through the built-in Go template function `js`
         {
           "match":
           {
-            "type": "payload-hash-sha1",
+            "type": "payload-hmac-sha1",
             "secret": "{{ getenv "XXXTEST_SECRET" | js }}",
             "parameter":
             {