If you are just looking for some CRF toolkit, python may not be a good choice.
According to my experience, a naive python implementation of linear-chained CRF (with numpy and scipy) can be 10 times slower than some popular CRF toolkits in other languages.
I recommend the CRFSuite
http://www.chokkan.org/software/crfsuite/ . It's fast and well-documented.