add copyright headers, update authors file

Author: Findeton

AUTHORS

@@ -1,4 +1,5 @@
 Eduardo Robles Elvira <edulix AT agoravoting DOT com>
 Javier Llorente Isidoro <javier AT agoravoting DOT com>
 Daniel García Moreno <danigm AT agoravoting DOT com>
-Victor Ramírez de la Corte <victor AT agoravoting DOT com>
+Victor Ramírez de la Corte <victor AT agoravoting DOT com>
+Félix Robles Elvira <felix AT agoravoting DOT com>

Gruntfile.js

@@ -1,3 +1,20 @@
+/**
+ * This file is part of agora-gui-admin.
+ * Copyright (C) 2015-2016  Agora Voting SL <agora@agoravoting.com>
+
+ * agora-gui-admin is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License.
+
+ * agora-gui-admin  is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+
+ * You should have received a copy of the GNU Affero General Public License
+ * along with agora-gui-admin.  If not, see <http://www.gnu.org/licenses/>.
+**/
+
 /*jslint node: true */
 'use strict';