Reorganize Presence related settings for consistency and completeness

darcs-hash:20091124123113-58252-bfe9a597d086d8c4d69b9aa13dcbb64c9b255402
Added support for xcap-directory application

Ignore-this: e59d4bc59efbd2a401201f068c945f0b

darcs-hash:20091125164240-56b4d-f02deaa5682e4c6bba23f44dab907faa4b59b2ed