corrected icon color hex values for mp6 light scheme; set file modification time for color schemes; fixed admin-bar text hover color for "site title" and "user account"; added background color to avatar frame (same as border color); restored `$menu-current-{...}` SASS variables (MP6 default is going to use them)

git-svn-id: https://plugins.svn.wordpress.org/mp6/trunk@774403 b8457f37-d9ea-0310-8a92-e5e31aec5664