Rewrite Adapter and Android Studio updates

PickerSpinnerAdapter doesn't make use of the super.getView and getDropdownView any more. Works perfectly now, only need to finalize the twin_text_item and twin_text_dropdown_item with the correct layout and text markups.
Updated Android Studio to 0.8.1 beta, but still running on old SDK and build tools (v19) until they are stable.