License cleanup in contrib/pyblosxom files
* README: Mention that contents of contrib/blosxom and contrib/pyblosxom
have different licenses than the rest of Muse.
* contrib/pyblosxom/getstamps.py: Add license text. It seems safe to
assume that the original author wanted this to be distributed with
Pyblosxom, and hence use the MIT license like the rest of Pyblosxom.
* contrib/pyblosxom/hardcodedates.py: Add license text.
* contrib/pyblosxom/make-blog: Change license text to be "This file may
be used, distributed, and modified without restriction."