message: Fix bug preventing partial group profile
  When updating the group profile, send empty strings instead of `null` as synapse does not expect `null`.
diff: @@ -524,8 +524,15 @@ export default React.createClass({
  },
  _onSaveClick: function() {
  + const newGroupProfile = this.state.profileForm;
  + // Synapse is not expecting `null`, so map unset values to the empty string
  + Object.keys(newGroupProfile).forEach((k) => {
  + if (!newGroupProfile[k]) {
  + newGroupProfile[k] = '';
  + }
  + });
  this.setState({saving: true});
  - MatrixClientPeg.get().setGroupProfile(this.props.groupId, this.state.profileForm).then((result) => {
  + MatrixClientPeg.get().setGroupProfile(this.props.groupId, newGroupProfile).then((result) => {
  this.setState({
  saving: false,
  editing: false,
  