Add button for filemanager. resolves #231

app/views/admin/_filemanager.html.erb

+<h3>Edit</h3>
+
+<a href="https://filemanager<%= Rails.configuration.deployment_environment['enote_domain_suffix'] %>/?expandedFolder=<%= my_course_id %>" target='blank' class="btn btn-default">Edit in Filemanager</a>
+
+<h3>Files</h3>
+
 <div class="container">
   <div class="row">
     <div class="col-md-8" style="display:none;">

app/views/admin/_sharelatex.html.erb

 
 <h3>Edit</h3>
-<a href="/sharelatex" target='blank' class="btn btn-default">Edit in Sharelatex</a>
 
+<a href="/sharelatex" target='blank' class="btn btn-default">Edit in Sharelatex</a>
 
 <h3>Compile</h3>