option to disable hostname validation during CA validation

There are circumstances where you still require a CA to validate that your key and cert are valid, but forgo verifying that the hostname matches the CN.

This is already done in TxMongo which uses Twisted's SSL Context Factory to achieve the same thing.

Example of use-case (outside of MongoDB):
http://www.symantec.com/business/support/index?page=content&id=TECH141351