Added slimerjs support to JS tests

Includes 7 squashed commits...
- Added slimerjs flag
- Fixed some bugs with flag code
- Figured out how to add arg correctly
- Cleanup
- Added print in controller to debug
- Capture output for slimerjs
- Fixed iptestcontroller rebase issues
Improvements to the test framework for FF
Added slimerjs to Travis
Fixed image test for slimerjs
Fixed indent .travis.yml
Comment out slimerjslauncher env var.
Comment out blank specific line
Added DEFAULT env
Symbolic link slimer
Sudo ln
Log to see if slimmer is actually running
Use slimerjs launcher env var
Make env vars more clear,
re-add SLIMERJS
Borrow casperjs yml to see if that works
Another travis config
Remove errorenous "." in front of etc path