Update Travis build process to generate resolution-independent CSS files.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>
Merge pull request #1875 from enyojs/fix-Travis-RI-aarontam

ENYO-721: Update Travis build process to generate resolution-independent CSS files.

Reviewed-By: Ryan Duffy (ryan.duffy@lge.com)
Integrated-By: Gray Norton (gray.norton@lge.com)