Background Animation & Focused Background

Two features are added.

• First one is for background color animation while selection. Animation duration can be changed with selectionAnimationDuration attribute from xml (or programmaticallysetSelectionAnimationDuration(int duration))
• Second one is for focused background color, which default value is selected background color with 16% of alpha. Default value can be changed with focusedBackgroundColor attribute from xml (or programmatically setFocusedBackgroundColor(int color))