Move Glyphicons into their own repo

Removes the icon fonts and associated docs and LESS code from the core
repo and into twbs/bootstrap-glyphicons.

less/bootstrap.less

@@ -28,7 +28,6 @@
 
 // Components: common
 @import "component-animations.less";
-@import "glyphicons.less";
 @import "dropdowns.less";
 @import "list-group.less";
 @import "panels.less";