1963 eunit bigcouch

This brings in the eunit tests for `config`. The top level PR for this is in apache/couchdb-couch#3 and this PR follows the same commit patterns for the most part.

Unfortunately most of the actual tests in this suite are disabled. There is some odd bug where `couch_log` when updates are made to `config` that I haven't been able to track down yet.

Also, in 405f677 I added a list of deps to start and stop for every tests. Not doing so resulted in unrelated test suites failing mysteriously. The way we currently start deps with `test_util:start_applications` is a hack and does not clean up after itself properly. I'm not a huge fan of the approach in 405f677 but at least it properly cleans up after itself.