Fix Travis build

  - Upgrades to new GeoTrellis namespace for vector.
  - Switches to manually installing transitfeed (there's a problem on Travis where pip does not work correctly with this module).
  - Runs tests for Scala and Django.
  - Removes Windshaft installation on Travis (not needed for tests, and causes PostGIS dependency issues on Travis -- the pre-installed PostGIS libraries become uninstalled).
  - Removes some commands from .travis.yml that were already being run in provision.sh, such as migrations. Initially I tried to remove all of the commands, but ran into some intricate permissions problems that caused me to add back in the npm/gem/grunt pieces.
  - Adds in some echo statements for easier diagnosing of problems in build.

With these updates, the build was passing on Travis. However, after rebasing to develop, there are newly broken Django tests related to authentication. Adding a separate issue to fix those tests.
Might we want to leave mapnik in for non-Travis installs?  I'm assuming we added that here because Windshaft says it needs it.