Add lock icon to a non public env var

assets/scripts/app/templates/env_vars.hbs

@@ -11,7 +11,7 @@
           Delete
         </a>
         <span class="name">{{name}}</span>
-        <span class="value value-display">{{value}}</span>
+        <span {{bind-attr class=":value :value-display public::secure"}}>{{value}}</span>
       {{/if}}
     </li>
   {{/each}}

assets/styles/settings.sass

@@ -104,6 +104,14 @@
     color: #838b8c
     font-family: monospace
 
+  span.value.value-display.secure
+    background-image: inline-image('ui/secure.png')
+    background-position: 8px center
+    background-repeat: no-repeat
+    background-size: 1.1em
+    padding-left: 26px
+    width: 384px
+
   .add-env-var, .add-ssh-key
     color: #ffffff
     background-color: #97a3aa