Fix observeOn() invocation order.

It should be called before lift() so that the operator can observe it on the main thread.
This change also adds some test for other bindXx() variants to get better coverage.
Rename OnSubscribe subclasses to OnSubscribeXx

This aligns RxJava convention.
Merge pull request #67 from omo/observeon-first

Fix observeOn() invocation order.
Merge pull request #77 from omo/onsubscribe

Rename OnSubscribe subclasses to OnSubscribeXx
Implementing an OnSubscribe that emits a Cursor as it moves to next.

This commit removes CursorIterableAdapter.java and implements the
Cursor navigation and safe closing in one place.

The option to use doOnTerminate(..) will not work as well to close
the Cursor since downstream operators while emiting errors would
not pass through the operator closing the Cursor.

Signed-off-by: David Marques <dpsmarques@gmail.com>