Allow to remove specific scores while leaving the reviewer listed

Currently only removal of reviewers is supported. This change implements
removal of specific scores while leaving the reviewer still listed on
the change.

Reviewer API is added for listing and deleting votes.

Bug: Issue 3035
Change-Id: Ie4f05fafb73a32835708a76eb86cfacf8ff5c670
diff --git a/Documentation/rest-api-changes.txt b/Documentation/rest-api-changes.txt
index 4679158..0b853c0 100644
--- a/Documentation/rest-api-changes.txt
+++ b/Documentation/rest-api-changes.txt
@@ -2264,6 +2264,55 @@
   HTTP/1.1 204 No Content
 ----
 
+[[list-votes]]
+=== List Votes
+--
+'GET /changes/link:#change-id[\{change-id\}]/reviewers/link:rest-api-accounts.html#account-id[\{account-id\}]/votes/'
+--
+
+Lists the votes for a specific reviewer of the change.
+
+.Request
+----
+  GET /changes/myProject~master~I8473b95934b5732ac55d26311a706c9c2bde9940/revisions/674ac754f91e64a0efb8087e59a176484bd534d1/files/ HTTP/1.0
+----
+
+As result a map is returned that maps the label name to the label value.
+The entries in the map are sorted by label name.
+
+.Response
+----
+  HTTP/1.1 200 OK
+  Content-Disposition: attachment
+  Content-Type: application/json;charset=UTF-8
+
+  )]}'
+  {
+    "Code-Review": -1,
+    "Verified": 1
+    "Work-In-Progress": 1,
+  }
+----
+
+[[delete-vote]]
+=== Delete Vote
+--
+'DELETE /changes/link:#change-id[\{change-id\}]/reviewers/link:rest-api-accounts.html#account-id[\{account-id\}]/votes/link:#label-id[\{label-id\}]'
+--
+
+Deletes a single vote from a change. Note, that even when the last vote of
+a reviewer is removed the reviewer itself is still listed on the change.
+
+.Request
+----
+  DELETE /changes/myProject~master~I8473b95934b5732ac55d26311a706c9c2bde9940/reviewers/John%20Doe/votes/Code-Review HTTP/1.0
+----
+
+.Response
+----
+  HTTP/1.1 204 No Content
+----
+
 [[revision-endpoints]]
 == Revision Endpoints
 
@@ -3747,6 +3796,10 @@
 === \{draft-id\}
 UUID of a draft comment.
 
+[[label-id]]
+=== \{label-id\}
+The name of the label.
+
 [[file-id]]
 \{file-id\}
 ~~~~~~~~~~~~