obfsproxy > 0.2.4 won't work in TBB because of missing PyYAML
obfsproxy > 0.2.4 needs PyYAML, and because of the way TBB building works, PyYAML needs to be installed explicitly (that is, just listing it in obfsproxy's setup.py is not sufficient to get the dependency installed during building).
We should try to include PyYAML in the TBB, because obfsproxy > 0.2.4 are the versions that support scramblesuit, connecting to outgoing proxies, etc.