support for multiple groups

Signed-off-by: Zolfa <zolfa@lilik.it>

static/add.html

@@ -33,6 +33,11 @@
                     <option ng-repeat="(key, value) in groups" value="{{key}}">{{value}}</option>
                 </select>
             </div>
+	    <div class="form-group">
+	         <label for="newExtraGroups">Gruppi aggiuntivi</label>
+		 <select multiple class="form-control" id="newExtraGroups" ng-model="newExtraGroups" ng-readonly="startConfirm">
+		     <option ng-repeat="(key,value) in groups | filter notPrincipal" value="{{key}}">{{value}}</option> 
+		 </select>
             <div class="form-group">
                 <label for="newUid">Username</label>
                 <input class="form-control" type="username" id="newUid" ng-model="newUid" placeholder="nome-utente" aria-describedby="newUidHelp" required ng-readonly="startConfirm" ng-keyup="typingUser()" />