Fix margin/gap inconsistency between 5.0 and pre-5.0

[chenxiaolong]

On pre-5.0, CardView (appcompat v7) adds a margin to draw the shadow. cardslib also adds a 6dp margin to the cards in ListViews and RecyclerViews, which results in large gaps between cards on pre-5.0 (see screenshots).

CardView has a card_view:cardUseCompatPadding attribute, which makes the 5.0 and pre-5.0 behavior match if set to true.

With this commit, ListView and RecyclerView now behave identically on <=4.4 and 5.0. (Also fixes shadows on the sides of cards on 5.0).

Platform	Before	After
4.4 ListView
4.4 RecyclerView
5.0 ListView
5.0 RecyclerView