Fix a bug about not firing user cancel event

Fix onActivityResult to handle result correctly.
Fix sever issues in StoreController.

Fix onActivityResult that ignore user cancel event.
Fix restoreTransaction: DONT query sku details to prevent network
connection.
Merge branch 'master' of https://github.com/HolymarsHsieh/android-store
Refactoring StoreController

Refactoring for Google IABv3.
The original code is too complex.
Clearify execution path for each public function.

Handle all situations properly and fire corresponding events.
Handle exceptions during purchase flow

If user leaves application (press home button, etc) during purchase
flow, there will be a null exception.
The may causes by a duplicated call to onCreate() function.
Arranged code and fixed small issues in StoreController
New events
Improvements and optimizations in StoreController:
1. Fixed Sync issues.
2. Helper is being started/killed before/after every operation.
3. Added functions to start/stop helper in background. This keeps it in the background and doesn't kill it between operations.
4. No need for StoreOpening and StoreClosing anymore.
Fixed example project and README.md to support new changes in StoreController
README.md supporting new changes in StoreController
handling purchase-state 1 or 2 as refund (1 is cancelled)
fixed function name
thanks @HolymarsHsieh