Support to retrieve a branch via REST

GET on /projects/<project-name>/branches/<branch-id> retrieves a
branch.

Change-Id: I1c2c81dcc5292d644d8048436c142039a4274e32
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

gerrit-server/src/main/java/com/google/gerrit/server/project/Module.java

@@ -53,6 +53,7 @@ public class Module extends RestApiModule {
     post(PROJECT_KIND, "gc").to(GarbageCollect.class);
 
     child(PROJECT_KIND, "branches").to(BranchesCollection.class);
+    get(BRANCH_KIND).to(GetBranch.class);
 
     child(PROJECT_KIND, "dashboards").to(DashboardsCollection.class);
     get(DASHBOARD_KIND).to(GetDashboard.class);