The "Groups" section's heading on user admin page was visible to mods

Since moderators can't manage a user groups, they shouldn't see the Groups heading on the user admin page.

## Before:

![before](https://cloud.githubusercontent.com/assets/17474474/25099135/c0e1d5a4-23b3-11e7-95d1-8036bff057d4.png)


## After:

![after](https://cloud.githubusercontent.com/assets/17474474/25099130/c060a538-23b3-11e7-8428-602fc523e9e8.png)

app/assets/javascripts/admin/templates/user-index.hbs

@@ -343,10 +343,9 @@
   </div>
 </section>
 
+{{#if currentUser.admin}}
   <section class='details'>
     <h1>{{i18n 'admin.groups.title'}}</h1>
-
-  {{#if currentUser.admin}}
       <div class='display-row'>
         <div class='field'>{{i18n 'admin.groups.automatic'}}</div>
         <div class='value'>{{automaticGroups}}</div>
@@ -367,8 +366,8 @@
           {{/if}}
         </div>
       </div>
-  {{/if}}
   </section>
+{{/if}}
 
 <section class='details'>
   <h1>{{i18n 'admin.user.activity'}}</h1>