Remove class name from buttons

The class names collide with built-in classes such as the "table" class in Bootstrap.
This results in the buttons inheriting the style from Bootstrap (or other frameworks) that define classes with those names.

src/js/easymde.js

@@ -232,7 +232,6 @@ function createToolbarButton(options, enableActions, enableTooltips, shortcuts,
         }
     }
 
-    el.className = options.name;
     el.setAttribute('type', markup);
     enableTooltips = (enableTooltips == undefined) ? true : enableTooltips;