add folder option to sidebar styling
remove whitespace
minimized folder keeps the gray color
use with with opacity instead of specific colors

toc-color-light is still in use elsewhere, so leaving it in
Merge branch 'master' into atc-sidebar-folder-styling

Conflicts:
	styles/variables.less
Merge pull request #98 from oerpub/atc-sidebar-folder-styling

Atc sidebar folder styling
Merge remote-tracking branch 'origin/master' into firefox-fixes
Configure less.js to dereference relative urls to the file it's in.

This is required for less.js 1.5.0, which in turn is needed to get this working
in firefox. It has to be set very early. Setting it in config.coffee seems
to be too late.
Account for the 1px borders on the sidebars.

Firefox is more strict about this. If you're off by these two pixels, the
editor is pushed off the screen and cannot be reached.
Mozilla specific width styling for ff < v16.