default sass vars + DOMContentLoaded "bugfix" by strajk

Hi,

First, thanks for the really cool work :)
My modest "contribution", not very used to pull requests... but I track your plugin with bower and fear I'll forget I modified your file, update it and loose my mods...

- I have a separate variables.scss file for sass init and declaring variables in it didn't seem to replace the defaults in your css/_breakpoints.scss file so I checked it: it was missing " !default" in vars declarations, so I added them and voilà, an even greater plugin :)
- Since I found that @Strajk's branch was a bit ahead and didn't break anything (and the fix seemed useful), I thought it'd be smarter to include it in the pull request instead of starting from an earlier version? ;
- Upped the version in bower.json.

Hope this is useful to you, and thanks again for the great work!