add nonull check to give a warning if js file is not included in the jsFile array
remove IE ms viewport code
update changelog
better travis check
add strip units function
remove all the CSS3 mixins
add hidpi min & max-width media queries
integrate strip-units function into responsive media queries
added `.promote-layer` helper class (from Web Starter Kit)
This may promote the layer to a composited layer.
use the modular-scale function to calculate the font sizes.
Now they're in the correct order
$bp-block-grid-narrow should always be smaller that $bp-single-col
remove old code
remove all empty media queries from `_global.scss`
add strip-units function to rem mixin
remove old tab focus mixin
moved functions and mixins import above variables so that the type scale works properly
updates checklist copy
compile css
Merge branch 'next' of https://github.com/tmwagency/kickoff into next

# By Ivan Hayes
# Via Ivan Hayes
* 'next' of https://github.com/tmwagency/kickoff:
  typos: fixed 'dofilesexist' task description.
  created a method to check for file existence

Conflicts:
	_grunt-configs/javascript.js
let autoprefixer do its thing