Update createRoom to support creating DM rooms

* Make ChatInviteDialog and MemberInfo createRoom use it
* Fix bug in setDMRoom

src/components/views/dialogs/ChatInviteDialog.js

@@ -257,9 +257,7 @@ module.exports = React.createClass({
 
     _startChat: function(addr) {
         // Start the chat
-        createRoom().then(function(roomId) {
-            return Invite.inviteToRoom(roomId, addr);
-        })
+        createRoom({dmUserId: addr})
         .catch(function(err) {
             var ErrorDialog = sdk.getComponent("dialogs.ErrorDialog");
             Modal.createDialog(ErrorDialog, {

src/components/views/rooms/MemberInfo.js

@@ -421,11 +421,7 @@ module.exports = React.createClass({
 
     onNewDMClick: function() {
         this.setState({ updating: this.state.updating + 1 });
-        createRoom({
-            createOpts: {
-                invite: [this.props.member.userId],
-            },
-        }).finally(() => {
+        createRoom({dmUserId: this.props.member.userId}).finally(() => {
             this.props.onFinished();
             this.setState({ updating: this.state.updating - 1 });
         }).done();