Create contractor dir if it doesn't exist

src/Conecto/Conecto.vala

@@ -49,8 +49,8 @@ namespace Conecto {
             build_version = "0.1";
         }
 
-        public override void activate ()
-        {
+        public override void activate () {
+            Contractor.create_if_not_exists_contract_dir ();
             Contractor.clean_contractor_directory.begin ();
             MConnectThread mconnect_thread = new MConnectThread (this, devices_map, main_settings);