.travis.yml: Call pants.bootstrap
.travis.yml: Remove line that cleans and tests java and scala stuff

It's failing in Travis CI
Try updating pytest from 2.3.5 to 2.5.2 in 3rdparty/python/BUILD
.travis.yml: Sync with
https://github.com/twitter/commons/blob/jsirois/sync/pants-1/.travis.yml
Merge pull request #212 from msabramo/travis_pants_bootstrap

Fix failing Travis builds: Travis pants bootstrap