Convert imports to ES6 from CommonJS

This is needed because `require()` means something different in webpack - it ends up importing the module as something we didn't expect (and is occasionally async)

src/utils/createMatrixClient.js

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import Matrix from 'matrix-js-sdk';
+import * as Matrix from 'matrix-js-sdk';
 
 const localStorage = window.localStorage;