Make travis load the required phantomjs version
Make travis load the required phantomjs version

Also improve caching for faster builds.

vitoravelino/velum,ereslibre/velum,kubic-project/velum,MaximilianMeister/velum,vitoravelino/velum,ereslibre/velum,kubic-project/velum,ereslibre/velum,ereslibre/velum,MaximilianMeister/velum,MaximilianMeister/velum,vitoravelino/velum,kubic-project/velum,MaximilianMeister/velum,kubic-project/velum,vitoravelino/velum