Add remote translation button

- Create partial to render remote translation button. This button will
  send remote_translations as json to remote translations controller.
- Add locales
- Add styles

Co-Authored-By: alessandro <agileontheweb@gmail.com>

app/assets/stylesheets/layout.scss

@@ -474,6 +474,26 @@ header {
     }
   }
 
+  .remote-translations-button {
+
+    .callout {
+      margin: 0;
+      padding: rem-calc(6);
+
+      [type="submit"] {
+        background: none;
+        border: 0;
+        cursor: pointer;
+        font-weight: bold;
+        color: $brand;
+
+        &:hover {
+          text-decoration: underline;
+        }
+      }
+    }
+  }
+
   .external-links {
     float: none;
     padding: rem-calc(6) 0;