Avoid doing mDNS lookups with dnspython

Ignore-this: 7f8261158ee9a5dea1e3be576222c89

darcs-hash:20130208145958-56b4d-dcbe263519eacc4e7102294713bbca289eea51c3
Added ability to properly stringify SDPSession objects

Ignore-this: 54729fbfbd60f6a893af61833d34f882

darcs-hash:20130213133422-56b4d-ebbe5d621cd9e3c66a83885120692b5252d895de