Upon card removal, put them back in mInternalObjects.

In CardArrayAdapter, notifyDataSetChanged() will now rebuild
mInternalObjects from the current list contents. However, this will
discard removed cards unless they are added back in upon swiping. Fix
this bug by adding removed cards back in.

Change-Id: Ib836fc8773b7a087090760e119094d2decc1ecf6