function setMessagesRead(state, _ref) {
	  var threadID = _ref.threadID;

	  return state.updateIn([threadID, "messages"], function (messages) {
	    return messages.map(function (msg) {
	      return msg.set("isRead", true);
	    });
	  });
	}
Mark all messages for a thread as "read"
@param {Immutable.Map}
@param {Object} payload
@param {GUID} payload.threadID