ZeroPortal setRawResult lua mode

This replaces the very hacky (and partially escaping broken) mode
where lua module decides to output data in the raw format.
Now, lua can set raw output data directly with
  mw.zeroportal.setRawResult(text)

This function is only enabled when used from Special:ZeroPortal.

Eventually, we might want to port this to the scribunto ext.

A second patch will remove current raw=1 code once code is fixed.

Change-Id: Ibb97523f6b3164268eaa80d94ddb001e7f6a6088