Merge no-ssl3-string-client-7686: disable SSLv3 in client string
endpoint parser

Author: Alex

Reviewer: glyph

Fixes: #7686

Use the default, correct behavior that Hynek has graciously bestowed
upon us.  We should be grateful for it.

git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/trunk@43398 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb