Update README
add license
clean up readme
Merge pull request #257 from binford2k/classroom_refactor

Classroom refactor
Give the modules a license and remove an old email address and tracker.
Merge pull request #258 from klynton/license-fix

Give the modules a license and remove an old email address and tracker.
Give p-t-b itself a License file.
Merge pull request #259 from klynton/again-license-fix

Give p-t-b itself a License file.