ConnectionManager/plug.upnp_connectionmanager.js
 - This file is changed by Rex Lee(http://github.com/rexboy7) to meet requriments of DLNA app in Gaia:
   - add prepareForConnection method

plug.upnp_contentdirectory.js:
 - This file is changed by Rex Lee(http://github.com/rexboy7) to meet requriments of DLNA app in Gaia.
   - maintain a configDocument property,
     stop suppressing exceptions,
     add mozSystem: true to XMLHttpRequest,
     and missellaneous.