fix .travis.yml from https://github.com/travis-ci/travis-ci/issues/2591
Correct parameter optionality

The last three parameters of ticker.addEventListener are optional. See: http://api.greensock.com/js/com/greensock/TweenMax.html#ticker
Merge pull request #2589 from allentc/master

Correct parameter optionality
fix SlickGrid declaration
Merge pull request #2591 from borisyankov/fix-slickgrid

fix SlickGrid declaration