Merge application-tests-names-7713

Author: eeshangarg
Reviewer: adiroiban, exarkun
Fixes: #7713

Rename all of the test case classes in `twisted.application.test` to conform to the
recently documented test case class naming convention.


git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/trunk@43509 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb