Port "mark reviewed" to new JSON API

Defines /changes/*/revisions/*/files/* as the JSON endpoint for file
resources, escaping / as %2F as in /projects. Add an endpoint
/reviewed under this to mark/unmark files as reviewed with PUT/DELETE.

Change-Id: I1de9934b709bdad8014d1d30a25703d7fd55be88

gerrit-server/src/main/java/com/google/gerrit/server/change/RevisionResource.java

@@ -47,7 +47,7 @@ public class RevisionResource implements RestResource {
     return ps;
   }
 
-  Account.Id getAuthorId() {
+  Account.Id getAccountId() {
     return ((IdentifiedUser) getControl().getCurrentUser()).getAccountId();
   }
 }