#52: fixed bug in find_available_port()
#52: a tad of clean up
#52: failures may be a thread timing issue; adding sleeps
Merge pull request #54 from RayPlante/astropydev

It appears that final problem causing Travis failures was that the test servers were not getting enough time to start up before a test would hit it. Hopefully, the added sleeps puts #52 to rest.
Merge branch 'master' of https://github.com/pyvirtobs/pyvo into readonly
Testing the last commit on pyvirtovs/pyvo