Make License.isCc() really return booleans

Before it returned undefined if the license had no internal name,
which caused unexpected behavior when used with $.toggle().

Change-Id: I1dcee6c999982fde47f9d388381fc670d81a6c5d
Mingle: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/494
Merge "Make License.isCc() really return booleans"