Buddy starter, new BuddyObject::initWithId, logout fix

* Added Buddy Starter sample that is a completely basic example of getting the SDK bootstraped and using the auth fail callback

* Add public initWithId ctor on BuddyObject to allow wrapping an object around a raw ID (e.g. profile picture ID).

* Fix logout to clear user token.

@nickatbuddy Leaving ```@synthesize``` without an ```= _passwordTextField``` will leave the backing ivar named ```passwordTextField```. It's not preferred ( to avoid confusion ), but the affect is the same. Not a big deal not to fix.