Force test failures to prove Travis isn't failing builds properly.
Ensuring drush returns a non-zero exit code on test failure.
Revert "Force test failures to prove Travis isn't failing builds properly."

This reverts commit 252f483a50bf4af783ad80cbdcf756f53129c0a9.
Noting reasoning for drush 5.x vs. 6.x.
Merge pull request #9 from iamEAP/test-fail

Fix for test build/fail regression.