Disable Gravatar (#37)

* Disable Gravatar
* Lowercase emails
* Add migration

templates/pages/admin_settings.html

@@ -37,6 +37,17 @@
                 </button>
             </div>
         </li>
+        <li class="list-none gap-x-4 py-5">
+            <div class="flex items-center justify-between">
+                <span class="flex flex-grow flex-col">
+                    <span class="text-sm font-medium leading-6 text-slate-300">Disable Gravatar</span>
+                    <span class="text-sm text-gray-400">Disable the usage of Gravatar as an avatar provider.</span>
+                </span>
+                <button type="button" id="disable-gravatar" data-bool="{{ .DisableGravatar }}" class="toggle-button {{ if .DisableGravatar }}bg-primary-600{{else}}bg-gray-400{{end}} relative inline-flex h-6 w-11 ml-4 flex-shrink-0 cursor-pointer rounded-full border-2 border-transparent transition-colors duration-200 ease-in-out focus:outline-none focus:ring-2 focus:ring-primary-600 focus:ring-offset-2" role="switch" aria-checked="false" aria-labelledby="availability-label" aria-describedby="availability-description">
+                    <span aria-hidden="true" class="{{ if .DisableGravatar }}translate-x-5{{else}}translate-x-0{{end}} pointer-events-none inline-block h-5 w-5 transform rounded-full bg-white shadow ring-0 transition duration-200 ease-in-out"></span>
+                </button>
+            </div>
+        </li>
     </ul>
     {{ .csrfHtml }}
 </div>