Add support for test coverage tracking with Coveralls

[japerry]

This adds PHPUnit code coverage generation and Coveralls (coveralls.io) integration. To implement it, connect your GitHub repository to Coveralls and make the following change to your .travis.yml:

@@ -29,7 +29,7 @@ jobs:
   include:
     - { name: "Static code analysis", env: ORCA_JOB=STATIC_CODE_ANALYSIS }
     - { name: "Deprecated code scan", env: ORCA_JOB=DEPRECATED_CODE_SCAN }
-    - { name: "Isolated test w/ recommended package versions", env: ORCA_JOB=ISOLATED_RECOMMENDED }
+    - { name: "Isolated test w/ recommended package versions and code coverage", env: ORCA_JOB=ISOLATED_RECOMMENDED ORCA_COVERALLS_ENABLE=TRUE }
     - { name: "Integrated test w/ recommended package versions", env: ORCA_JOB=INTEGRATED_RECOMMENDED }
     - { name: "Integrated test w/ recommended package versions & previous minor release of Drupal core", env: ORCA_JOB=CORE_PREVIOUS }
     - { name: "Isolated test w/ dev package versions", env: ORCA_JOB=ISOLATED_DEV }

Fixes #95, closes #96. (Thanks, @swichers!)

[japerry]

@TravisCarden this appears to have tested correctly, however coveralls isn't detecting the PR. I've replicated everything from PR51, is there something else that has to happen on the coveralls side to get it to show up?
https://coveralls.io/github/acquia/orca

[swichers]

@TravisCarden Bit late now, but I'm not a big fan of a specific service like Coveralls being forced if you also want coverage data collected. There are a lot of services out there that pull in clover files. I don't see a way to collect coverage data and not use php-coveralls without having to replace ORCA scripts.

Would really love if ORCA checked if php-coveralls was present before trying to run it. The coveralls requirement could also be moved to suggest in the composer.json. This would let people be able to use whatever code coverage solution they want without having to completely replace ORCA scripts. They could leave ORCA defaults as-is and just add additional scripts with their specific needs.

[TravisCarden]

That's helpful feedback, @swichers, thank you. Let's continue the conversation on #106.