Moved resources_to_operations to internal nbi.py valid_url_methods to avoid inconsistences

refactored session variable into token_info, engine_session, cherrypy.session to bring more clarity
commented unnecesary exception logs
inserted admin query string into roles permissions

Change-Id: Ib3d9d3210e4eb894a3f120c26f6d0ce032ebc797
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>