Fetch builds for branches from /builds endpoint (closes #123)

assets/scripts/app/models/build.coffee

@@ -70,6 +70,9 @@ require 'travis/model'
   byRepoId: (id, parameters) ->
     @find($.extend(parameters || {}, repository_id: id))
 
+  branches: (options) ->
+    @find repository_id: options.repoId, branches: true
+
   olderThanNumber: (id, build_number) ->
     # TODO fix this api and use some kind of pagination scheme
     @find(url: "/builds", repository_id: id, after_number: build_number)

assets/scripts/app/models/repo.coffee

@@ -62,7 +62,7 @@ require 'travis/model'
   ).property()
 
   branches: (->
-    Travis.Branch.byRepoId @get('id')
+    Travis.Build.branches repoId: @get('id')
   ).property()
 
   events: (->