Slightly improve license handling in controller

Enumerated licenses are a *class* variable, not instance
Must update license description when updating key!

NOTE: *by_sa* looks wrong!  Certainly inconsistent.

TODO: Fix by_sa in data and code.
TODO: Model rights in a common gem!
TODO: Stop storing "human" license at all.  Pull it based on key.
TODO: Use FULL URI for identifying license, including VERSION number.
TODO: Fix all the other broken heads that munge license data in the
same way, i.e. without identifying version or using a different "human" license
text.