Render template variables manage button based on authorization

Signed-off-by: Jared Scheib <jared.scheib@gmail.com>

ui/src/dashboards/components/TemplateControlBar.js

@@ -2,6 +2,8 @@ import React, {PropTypes} from 'react'
 import classnames from 'classnames'
 import calculateSize from 'calculate-size'
 
+import Authorized, {EDITOR_ROLE} from 'src/auth/Authorized'
+
 import Dropdown from 'shared/components/Dropdown'
 
 const minTempVarDropdownWidth = 146
@@ -75,6 +77,7 @@ const TemplateControlBar = ({
               This dashboard does not have any Template Variables
             </div>}
       </div>
+      <Authorized requiredRole={EDITOR_ROLE}>
         <button
           className="btn btn-primary btn-sm template-control--manage"
           onClick={onOpenTemplateManager}
@@ -82,6 +85,7 @@ const TemplateControlBar = ({
           <span className="icon cog-thick" />
           Manage
         </button>
+      </Authorized>
     </div>
   </div>