Build and install from GOPATH

* Rename 'vendor/src' -> 'vendor'
  * Ignore vendor/ instead of vendor/src/ for lint
* Rename 'cmd/client' -> 'cmd/ocic' to make it 'go install'able
* Rename 'cmd/server' -> 'cmd/ocid' to make it 'go install'able
* Update Makefile to build and install from GOPATH
* Update tests to locate ocid/ocic in GOPATH/bin
* Search for binaries in GOPATH/bin instead of PATH
* Install tools using `go get -u`, so they are updated on each run

Signed-off-by: Jonathan Yu <jawnsy@redhat.com>

vendor/github.com/mistifyio/go-zfs/error.go

@@ -0,0 +1,18 @@
+package zfs
+
+import (
+	"fmt"
+)
+
+// Error is an error which is returned when the `zfs` or `zpool` shell
+// commands return with a non-zero exit code.
+type Error struct {
+	Err    error
+	Debug  string
+	Stderr string
+}
+
+// Error returns the string representation of an Error.
+func (e Error) Error() string {
+	return fmt.Sprintf("%s: %q => %s", e.Err, e.Debug, e.Stderr)
+}