Remove unused testing templates and unused tabs.

common/lib/xmodule/xmodule/js/fixtures/html-edit-formattingbug.html

-<section class="html-edit">
-    <textarea class="tiny-mce">dummy</textarea>
-<!--
-TODO: DELETE THIS FILE
-    The text passed in is the escaped version of
-    &lt;problem>
-    &lt;p>&lt;/p>
-    &lt;multiplechoiceresponse>
-    <pre>&lt;problem>
-        &lt;p>&lt;/p></pre>
-    <div><foo>bar</foo></div>
--->
-    <textarea name="" class="edit-box">&amp;lt;problem&gt;
-&amp;lt;p&gt;&amp;lt;/p&gt;
-&amp;lt;multiplechoiceresponse&gt;
-&lt;pre&gt;&amp;lt;problem&gt;
-    &amp;lt;p&gt;&amp;lt;/p&gt;</pre>
-<div><foo>bar</foo></div></textarea>
-</section>
\ No newline at end of file

common/lib/xmodule/xmodule/js/fixtures/html-edit-with-links.html

-<section class="html-edit">
-    <ul class="editor-tabs">
-        <li><a href="#" class="visual-tab tab current" data-tab="visual">Visual</a></li>
-        <li><a href="#" class="html-tab tab" data-tab="advanced">HTML</a></li>
-    </ul>
-    <div class="row">
-        <textarea class="tiny-mce">dummy text</textarea>
-        <textarea name="" class="edit-box">Advanced Editor Text with link /static/dummy.jpg</textarea>
-    </div>
-</section>
\ No newline at end of file

common/lib/xmodule/xmodule/js/fixtures/html-edit.html

 <section class="html-edit">
-    <ul class="editor-tabs">
-        <li><a href="#" class="visual-tab tab current" data-tab="visual">Visual</a></li>
-        <li><a href="#" class="html-tab tab" data-tab="advanced">HTML</a></li>
-    </ul>
-    <div class="row">
     <textarea class="tiny-mce">dummy text</textarea>
-        <textarea name="" class="edit-box">Advanced Editor Text</textarea>
-    </div>
 </section>

lms/templates/widgets/html-edit.html

 <%! from django.utils.translation import ugettext as _ %>
 
 <section class="html-editor editor">
-  <ul class="editor-tabs">
-    <li><a href="#" class="visual-tab tab current" data-tab="visual">${_("Visual")}</a></li>
-    <li><a href="#" class="html-tab tab" data-tab="advanced">${_("HTML")}</a></li>
-  </ul>
-
   <div class="row">
     <textarea class="tiny-mce">${data | h}</textarea>
-    <textarea name="" class="edit-box">${data | h}</textarea>
   </div>
 </section>