Changed the interface on AbstractAdapter to require that adapters return the number of affected rows on delete and update operations. Added that Base.update_all and Base.delete_all return an integer of the number of affected rows #341

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@228 5ecf4fe2-1ee6-0310-87b1-e25e094e27de