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

test/hooks.json.tmpl

@@ -31,7 +31,7 @@
         {
           "match":
           {
-            "type": "payload-hash-sha1",
+            "type": "payload-hmac-sha1",
             "secret": "mysecret",
             "parameter":
             {
@@ -288,7 +288,7 @@
         {
           "match":
           {
-            "type": "payload-hash-sha1",
+            "type": "payload-hmac-sha1",
             "secret": "mysecret",
             "parameter":
             {

test/hooks.yaml.tmpl

@@ -8,7 +8,7 @@
           source: header
           name: X-Hub-Signature
         secret: mysecret
-        type: payload-hash-sha1
+        type: payload-hmac-sha1
     - match:
         parameter:
           source: payload
@@ -174,4 +174,4 @@
           source: header
           name: X-Hub-Signature
         secret: mysecret
-        type: payload-hash-sha1
+        type: payload-hmac-sha1