Allow the . (dot) and @ (at) character in usernames (#637)

Co-authored-by: Uli Koeth <uli@kiot.eu>

docs-web/src/main/webapp/src/partial/docs/settings.user.edit.html

@@ -9,7 +9,7 @@
       <label class="col-sm-2 control-label" for="inputUserUsername">{{ 'settings.user.edit.username' | translate }}</label>
       <div class="col-sm-7">
         <input name="userUsername" type="text" id="inputUserUsername" required ng-disabled="isEdit()" class="form-control"
-               ng-pattern="/^[a-zA-Z0-9_]*$/"
+               ng-pattern="/^[a-zA-Z0-9_@\.]*$/"
                ng-minlength="3" ng-maxlength="50" ng-attr-placeholder="{{ 'settings.user.edit.username' | translate }}" ng-model="user.username"/>
       </div>
 
@@ -129,4 +129,4 @@
       </div>
     </div>
   </form>
-</div>
+</div>