ENYO-2424: Modify onyx.Popup zIndex selection to pick adequately high z-index values for popups on top of other popups

Based on code suggested in bug by Chris Van Hooser

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Merge pull request #158 from enyojs/ENYO-2424-unwiredben

ENYO-2424: Modify onyx.Popup zIndex selection to pick adequately high z-...
Update Popup.js

Fix change for ENYO-2424 by using static name that matches the code.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Add jshint checking for travis-ci for onyx
Clean up an error found by jshint in ContextualPopup.js - use of wrong value.

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Add missing period after jshint in .travis.yml

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Reverse fix from jshint-detected error -- should be using innerHeight here

Enyo-DCO-1.1-Signed-Off-By: Ben Combee (ben.combee@lge.com)
Merge pull request #159 from enyojs/travisci-jshint

Travisci jshint

Reviewed-By: Gray Norton <gray.norton@lge.com>
Merge branch 'master' of github.com:enyojs/onyx into ENYO-2431