Release of 0.22.0

- Merge pull request #20 from naghtarr/naghtarr/itemclicks
- Move OperatorSharedPreferenceChange to rx.android.operators package
- Merge branch '0.x' to 'naghtarr/itemclicks'
- Merge pull request #25 from Yarikx/shared-preferences-observable
- Merge pull request #22 from mironov-nsk/view-observables
- Merge pull request #29 from egor-n/0.x
- Fix a typo in the docs
- remove isUnsubscribed call befor item emittion
- Break up tests from OperatorAdapterViewOnItemClickTest into separated scenarios
- Add fromSharedPreferencesChanges Observable
- Update gitignore file
- Make OnItemClickEvent class non-final
- Remove useless generics regarding OperatorAdapterViewOnItemClick
- Move OperatorAdaperViewOnItemClick to rx.android.operators package
- Remove useless generics, prodive some helper methods
- Move operators under the rx.android package
- Use custom events for ViewObservables
- Add OperatorAdapterViewOnItemClick to observe OnItemClick events in AdapterViews. Resolve #19.
