Revert change from index to find.

Refs: #5005

git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/branches/twisted-web-remove-text-5004@39082 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb
Fix some twistedchecker errors.

git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/branches/twisted-web-remove-text-5004@39083 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb
Whitespace.

git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/branches/twisted-web-remove-text-5004@39084 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb
Add docstrings to t.web.test.requesthelper.DummyRequest