Split out Boost.Python
boost-python: drop build option pass-through to boost
boost-python: syntax
boost-python: trim some fat
boost: put user-paths back

I thought this was a bad Python hack but git blame told me that it helps
build MPI, from 937d81bdd23d6df29e337.
boost-python: add test
boost: update 1.55.0_2 bottle.
boost-python: add 1.55.0 bottle.