Added xcap to lists of python packages

Ignore-this: a591d0e4c373f247a64014c582523019

darcs-hash:20100831152201-58252-63f55a77f0aad1a019ba56573dd65c6b0eb15c27
Improved logic of adding a contact to presence or dialog subscription lists

Ignore-this: f03437ec2a8a22b3ccdf4a8b8ac0e7ce

darcs-hash:20100831161015-1e3d8-630273ec26e9be9e4fc014a6a3cf8aec6b387a22