Handle accountData events from TagOrderStore

This introduces a generic way to register certain events emitted by
the js-sdk as those that should be propagated through as dispatched
actions.

This allows the store to treat the js-sdk as the "Server" in the
Flux data flow model. It also allows for stores to not be aware
specifically of the matrix client if they are only reading from it.

src/actions/GroupActions.js

@@ -14,7 +14,6 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-
 import { createPromiseActionCreator } from './actionCreators';
 
 const GroupActions = {};