VBInputSourceManager listening to own user and immediately sending notifications after mic processed.

Re:issue #15

- added property listenToUser on VBInputSourceManager which sets the current user to listen to (can be self or nil for listening to own mic)
- added isSubscribedToOwnMicInput to figure out whether it should listen to network pub sub notifications or just results of it’s own mic for immediate NSNotification
- Added pushing to a user channel if logged in.
Merge pull request #38 from azoff/15-core-vbusermic

VBInputSourceManager listening to own user and immediately sending notifications after mic processed.
Check In Methods

Closes #33

- Adds checkin method to VBFoursquare
- Adds checkin method to VBUser
- Adds VBFoursquareObject parent class for models (guarentees uniqueness, atomic upsert)
- Adds test for user checkin