Change the travis config a bit
Change the travis config a bit

There is no use in doing code coverage for the code installed into the
virtualenv. However, coverage for tests ensures there isn't dead code
in tests that isn't running when it should.

deniszh/whisper,graphite-server/whisper,penpen/whisper,kerlandsson/whisper,alexandreboisvert/whisper,obfuscurity/whisper,graphite-project/whisper,piotr1212/whisper,jjneely/whisper,akbooer/whisper,cbowman0/whisper