[Bounty $20] Some unit tests skipped without being ignored on travis

[freemo]

For some reason some unit tests are skipped even though they are not ignored on travis. On my local computer with a gpu this doesnt seem to be the case.

[yejingyan]

I would like to claim this bounty.

I opened PR #190 to fix the Travis test-skip configuration: the matrix used RUN_TEST=false while the global variable was RUN_TESTS=true, and Travis had no explicit script: section. The PR makes the variable consistent and gates mvn test vs mvn -DskipTests package on RUN_TESTS.