* src/sugar/activity/activity.py: Get the shared activity wrapper from
sugar.presence.
* src/sugar/activity/activityfactory.py: Disable checking in the PS for
activity_id duplicates.
* src/sugar/presence/activity.py: Remove the PS dependency and query Telepathy
directly. Implemented enough to join an activity.
* src/sugar/presence/buddy.py: Remove the PS dependency and query Telepathy
directly. Implemented enough to join an activity. Added an Owner subclass of
Buddy()
* src/sugar/presence/presenceservice.py: Remove the PS dependency and query Telepathy
directly. Implemented enough to join an activity.
* src/sugar/presence/util.py: Add ConnectionManager for discovering and tracking
connections.