[Fronted] Significant refactoring of btn classes

WTD-839
Refactoring in advance of style mods to switcher when in frame;
Moved btn styles from _controls.scss to _buttons.scss;
Markup cleaned up with css classing simplified;

platform/commonUI/edit/res/templates/topbar-edit.html

@@ -33,8 +33,6 @@
         <mct-representation key="'edit-action-buttons'"
                             mct-object="domainObject"
                             class='conclude-editing'>
-		<!--a class='btn major' href=''>Save<span id='save-actions-menu' class='ui-symbol invoke-menu'>v</span></a>
-		<a class='btn subtle' href=''>Cancel</a-->
         </mct-representation>
     </div>
 </div>