pmt: added python converters
core: added tag to python converters
build: disable certain Boost versions we know are buggy to fix Issue #513.

Creates a new list of version to test against. If any version matches the list of bad versions, set Boost to Not Found.
Merge branch 'maint'
Merge branch 'pmt_to_python'
Merge branch 'master' of git://github.com/gnuradio/gnuradio into ofdm
Merge branch 'ofdm' of github.com:benreynwar/gnuradio into ofdm