Add sidebars for ad spaces. Top of front page and below lead reply.
Begin adjustment of LESS variables. Centralize. Test new color scheme.
Centralize variables in bootstrap LESS. Tweaks to bbpress's CSS.
Color scheme is now controlled by a small set of variables, located in
variables.less, and every other color in the scheme is derived from those.

The bbpress css tweaks were to add control in Serverus's files, as some of the
styles were still in bbpress's hands.
Tweak profile page CSS so it matches theme colors/bootstrap.
Add -muted variables to the color scheme.