Add static methods to retrieve Cards.

Add methods to retrieve DataCard and DataCardImage objects for all
currently published cards in the ContentProvider.

Change-Id: I4e6390cff6283ad0d79b94f9255b91698fd2f1f5
Close cursors and add Images for Card retrieval.

Make sure all cursors are closed after querying. Add logic to retrieve
all DataCardImages when a DataCard is loaded.

Change-Id: I29591e785760112efd206e2cfff254f8cb2b1054