Refactored out methods wrt lazy-loading views in @AndroidFragment and @AndroidActivity.

@CustomViewGroup has the same magic powers as the previous two.
@AndroidView is no longer necessary.

Fixed some NPEs as a result from the refactoring.
Merge pull request #29 from Buggaboo/merge_upstream_refactored_out_view_lazy_loading_getters

Refactored out methods wrt lazy-loading views in @AndroidFragment and @A...