Forward port changes to the invitation handling from proko2.
Forward port changes to the invitation handling from proko2.

svn path=/trunk/kdepim/; revision=355773

lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi