[Frontend] Significant re-factoring of CSS and markup

open #95
IN-PROGRESS!;
Mostly buttons and menus classes (s-btn and s-menu);
Removed unused templates and .css files;
Normalized some button containers;

platform/forms/res/templates/controls/button.html

@@ -19,7 +19,7 @@
  this source code distribution or the Licensing information page available
  at runtime from the About dialog for additional information.
 -->
-<a class="t-btn l-btn s-btn s-icon-btn s-very-subtle"
+<a class="s-btn"
    ng-class="{ labeled: structure.text }"
    ng-click="structure.click()">
     <span class="ui-symbol icon">