Bug 949880 - Part 0: Unify redundant constants and add Utils.nodeWeaveURL.
Bug 949880 - Part 1: Factor out concrete RecordFactory instances.
Bug 949880 - Part 2: Split GlobalSessionCallback into BaseGlobalSessionCallback and NodeAssignmentCallback.
Bug 949880 - Part 3: Factor SharedPreferencesClientsDataDelegate out of SyncAdapter.
Bug 949880 - Part 4: Factor SharedPreferencesNodeAssignmentCallback out of SyncAdapter.
Bug 949880 - Part 5: Remove SyncConfiguration.serverURL entirely.
Bug 949880 - Part 6: Remove unused serverURL (nodeWeaveURL) from GlobalSession constructor.
Bug 949880 - Part 7: Prevent NPEs by guarding constructors.
Bug 949880 - Refactor android-sync SyncAdapter for FxAccount use. r=rnewman