Also clean up the license hash checking a bit. We trim vendor early
in find so we don't have to walk the whole vendor tree only to grep
the files out, and we don't check the license hashes of the exceptions,
and the exceptions are now a plain text file of non-regex strings
we match exactly. Also the license hash code is only written once.
This will help us a lot if development on Pilosa continues through
2018 or later.