Revisions: Add a new test for a force save filter in wp_save_post_revision

Also Update the tests to have correct ordering, be less complex and use things like assertCount.
See #7392 and #9843 


git-svn-id: https://unit-tests.svn.wordpress.org/trunk@1214 4a5a2adb-35eb-4268-9a1b-fe04a4134342