Drop the accordion for the panel

* Deletes the accordion.less file
* Extends the panel to be collapsible with our JS plugin
* Supports panel color variations

less/bootstrap.less

@@ -55,7 +55,6 @@
 @import "labels.less";
 @import "badges.less";
 @import "progress-bars.less";
-@import "accordion.less";
 @import "carousel.less";
 @import "jumbotron.less";