Github API and search by license: consider this for improved detection

See "Searching GitHub by license type" https://help.github.com/articles/licensing-a-repository/

These may be material for new license rules?

> You can filter repositories based on their license or license family using the license qualifier and the exact license keyword:

License | License keyword
---------- | ----------
Academic Free License v3.0 | afl-3.0
Apache license 2.0 | apache-2.0
Artistic license 2.0 | artistic-2.0
Boost Software License 1.0 | bs1-1.0
BSD 2-clause "Simplified" license | bsd-2-clause
BSD 3-clause "New" or "Revised" license | bsd-3-clause
BSD 3-clause Clear license | bsd-3-clause-clear
Creative Commons license family | cc
Creative Commons Zero v1.0 Universal | cc0-1.0
Creative Commons Attribution 4.0 | cc-by-4.0
Creative Commons Attribution Share Alike 4.0 | cc-by-sa-4.0
Do What The F*ck You Want To Public License | wtfpl
Educational Community License v2.0 | ecl-2.0
Eclipse Public License 1.0 | epl-1.0
European Union Public License 1.1 | eupl-1.1
GNU Affero General Public License v3.0 | agpl-3.0
GNU General Public License family | gpl
GNU General Public License v2.0 | gpl-2.0
GNU General Public License v3.0 | gpl-3.0
GNU Lesser General Public License family | lgpl
GNU Lesser General Public License v2.1 | lgpl-2.1
GNU Lesser General Public License v3.0 | lgpl-3.0
ISC | isc
LaTeX Project Public License v1.3c | lppl-1.3c
Microsoft Public License | ms-pl
MIT | mit
Mozilla Public License 2.0 | mpl-2.0
Open Software License 3.0 | osl-3.0
PostgreSQL License | postgresql
SIL Open Font License 1.1 | ofl-1.1
University of Illinois/NCSA Open Source License | ncsa
The Unlicense | unlicense
zLib License | zlib