Removing unused declared attributes

ABS currently declares a number of attributes that are never used.
As they're not useful for neither the library nor developers[1], I think it's reasonable to remove them:
* listPreferredItemHeightSmall
* listPreferredItemPaddingLeft
* listPreferredItemPaddingRight
* textAppearanceListItemSmall
* windowMinWidthMajor
* windowMinWidthMinor
* actionSpinnerItemStyle
* horizontalDivider
* verticalDivider
* headerBackground
* windowAnimationStyle
* itemIconDisabledAlpha

[1] there aren't any values set for them on ABS' themes