chore(travis): don't call grunt:package for unit tests

Unit tests are run against the src files or against the unminified build
files (tests:modules). This shaves off 1 minute of the unit test task.
Nice to have if you just want to know that they pass

Author: Narretz

scripts/travis/before_build.sh

@@ -12,7 +12,10 @@ fi
 npm install -g grunt-cli
 
 if [ $JOB != "ci-checks" ]; then
-  grunt package
+  # unit tests test don't test against packaged (minified) files
+  if [ $JOB != "unit" ]; then
+    grunt package
+  fi
   echo "wait_for_browser_provider"
   ./scripts/travis/wait_for_browser_provider.sh
 fi