fixes the highlight styles
adding icons for highlight
Merge branch 'develop' of github.com:scholarslab/prism into develop
Merge fix.

Merge branch 'develop' of github.com:scholarslab/prism into develop

Conflicts:
	app/assets/stylesheets/media/_screen.scss
	app/views/prisms/highlight.html.erb
Merge branch 'develop' of github.com:scholarslab/prism into develop
changes base variables // reverts to earlier highlight css
changes highlight styles
Merge branch 'develop' of github.com:scholarslab/prism into develop
sets color variables