Merge m-c to s-c.

Merge mozilla-central into services-central

Merge m-c to s-c.

Merge m-c to s-c.

Bug 787306 - Fix bitrotted Sync UX code; r=rnewman services-central contains lots of changed code. Sync UX changes which landed in inbound for bug 762230 are not compatible with the future.

Merge m-c to s-c.

Bug 786489 - Part 2: Change username through Identity not prefs; r=rnewman The preferred way to change the username is through the Identity singleton, not by updating a pref and hoping the side-effect is what you want.

Bug 786489 - Part 1: Update serverURL and clusterURL through Service; r=rnewman The preferred method to update serverURL and clusterURL is by going through the SyncService Service singleton, not by setting preferences.

Bug 785225 - Part 11: Burninate trailing whitespace from tests; r=rnewman

Bug 785225 - Part 10: Reflect API changes in TPS; r=rnewman The previous parts broke TPS. This fixes them all in one lump patch.

Bug 785225 - Part 9: Refactor engines to not use singletons; r=rnewman Engines now maintain a reference to the service they belong to. This allows them to obtain references to other engine instances belonging to that service and that service only. Stores and trackers now maintain a reference to the engine they belong to. Engine managers now maintain a reference back to a service. The clients singleton has been removed. It now exists as an instance variable on Service. Parts of ClientsEngine do behave as singletons (e.g. commands). This will be addressed in future refactoring.

Bug 785225 - Part 8: Don't expose SyncScheduler as a singleton; r=rnewman

Bug 785225 - Part 7: Bind SendCredentialsController to a Service instance; r=rnewman

Bug 785225 - Park 6: Move StorageCredentialsController to jpakeclient.js; r=rnewman I'm not sure why it was in policies.js, as it has everything to do with J-PAKE exchange.

Bug 785225 - Part 5: Partial removal of Clients singleton; r=rnewman Clients was being exported and used as a singleton. We still use Clients as a singleton in some places, but only in test code. The preferred method to access Clients is now through a service instance. Weave.Clients is no longer exposed. Callers go through Weave.Service now.

Bug 785225 - Part 4: Remove unused exports from Weave; change engine loading; r=rnewman Lots of exports from the Weave global object weren't being used. This also changes how engines are loaded. There is now a mapping in service.js of engine name to filename. Before, it was looking at Weave.

Bug 785225 - Part 3: Don't expose ErrorHandler as a singleton; r=rnewman Some tests still expect there to only be a single instance of ErrorHandler for the life of the tests. And, ErrorHandler itself is pretty tighly coupled with being a singleton because it writes out changes to prefs, etc. But, it's a step in the right direction.

Bug 785225 - Part 2: Minimize Engines singleton usage; r=rnewman Weave.Engines is no longer exported. Service now exposes an EngineManager instance, which is the new recommended way to get at the engine manager. Service was updated to reference the internal instance.

Bug 785225 - Part 1: Don't rely on Engines singleton in AddonsReconciler; r=rnewman

Bug 783721 - Refactor User API service interaction; r=rnewman