Another attempt at configuring Python in Travis

Author: Michael Koval

.travis.yml

@@ -1,14 +1,24 @@
-sudo: required
 dist: trusty
+sudo: required
+env:
+  global:
+  - REPOSITORY=prpy
+# Allow Python to find packages installed by apt.
+# See: http://docs.travis-ci.com/user/languages/python/#Travis-CI-Uses-Isolated-virtualenvs
+language: python
+python:
+- '2.7'
 virtualenv:
   system_site_packages: true
-env:
-- REPOSITORY=prpy
-install:
+# Install test fixture dependencies.
+before_install:
 - git clone https://github.com/personalrobotics/pr-cleanroom.git
 - cd pr-cleanroom
 - curl -O https://raw.githubusercontent.com/personalrobotics/pr-rosinstalls/feature/rosdistro/repositories.yml
 - ./internal-setup.sh
+# Checkout this repository and all of its dependencies.
+install:
 - ./internal-distro.py --workspace=src --repository "${REPOSITORY}" distribution/distribution.yml
+# Build the workspace and run tests.
 script:
 - ./internal-build.sh $(./internal-get-packages.py repositories.yml "${REPOSITORY}")