fix(build): fix bootstrap glyphicons

I removed the `cssmin root option` in the `Gruntfile.js` and updated the font path in the `main.scss`.

I think we can deal with the remove of the `root option` cause it only replaces relative paths into absolute paths. [link](https://github.com/GoalSmashers/clean-css#how-to-use-clean-css-cli)

I also updated the fonts to the newest version.

`grunt build` should now work correctly for bootstrap glyphicons with and without sass.