Update release documents

Remove redundant AUTHORS file in favor of relying
on .mailmap for keeping track of author names.
Move older changelogs to release directory.
Move release checklist to releases README.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

releases/v2.5.0-changelog.txt

@@ -0,0 +1,33 @@
+# Changelog
+
+## 2.5.0 (2016-06-14)
+
+#### Storage
+- Ensure uploads directory is cleaned after upload is committed
+- Add ability to cap concurrent operations in filesystem driver
+- S3: Add 'us-gov-west-1' to the valid region list
+- Swift: Handle ceph not returning Last-Modified header for HEAD requests
+- Add redirect middleware
+
+#### Registry
+- Add support for blobAccessController middleware
+- Add support for layers from foreign sources
+- Remove signature store
+- Add support for Let's Encrypt
+- Correct yaml key names in configuration
+
+#### Client
+- Add option to get content digest from manifest get
+
+#### Spec
+- Update the auth spec scope grammar to reflect the fact that hostnames are optionally supported
+- Clarify API documentation around catalog fetch behavior
+
+#### API
+- Support returning HTTP 429 (Too Many Requests)
+
+#### Documentation
+- Update auth documentation examples to show "expires in" as int
+
+#### Docker Image
+- Use Alpine Linux as base image