message: Fix starting a chat by email address
  Regression introduced whilst refactoring for groups support.
diff: @@ -127,7 +127,7 @@ function _onRoomInviteFinished(roomId, shouldInvite, addrs) {
  }
  function _isDmChat(addrTexts) {
  - if (addrTexts.length === 1 && getAddressType(addrTexts[0])) {
  + if (addrTexts.length === 1 && getAddressType(addrTexts[0]) === 'mx') {
  return true;
  } else {
  return false;
  