Basic Tabs now inherit from a Bootstrap Theme

Tabs were pretty basic.  For the most, tabs were using the standard
styles nicely, except when embedded inside of a modal. There was a
lot of adding padding and removing padding to the tab-content and
modal container.  This has been cleaned up.

Also, the 'asterisk' that is used to show when a tab has required
information for a workflow was changed to an icon font.

Many unused styles were removed from horizon.scss.

Partially-Implements: blueprint horizon-theme-css-reorg
Partially-Implements: blueprint bootstrap-html-standards

Change-Id: I929de0ae31a3c2cca9e332956eed755c4e279f3d

openstack_dashboard/themes/material/static/horizon/_icons.scss

@@ -54,6 +54,7 @@ $icon-swap: (
   share-square-o: 'share',
   link: 'link-variant',
   exchange: 'swap-horizontal',
+  asterisk: 'star',
 );
 
 @each $fa-icon, $mdi-icon in $icon-swap {