[Android] Make CoreSelection and HistorySelection statically instantiable.

Allows showing the dialogs without the need for an actual variable or ugly "new HistorySelection(fm, tag).show();" syntax.

Also moved the else if for "Quit Retroarch" to the bottom of the if statements so its structured relative to the UI.
[Android] Make a field a local variable in DisplayRefreshRateTest. It's not used elsewhere, so this is safe.
Merge pull request #397 from lioncash/master

Misc cleanup