public async void OnButtonClickedLogOff(object sender, EventArgs e)
		{
			var db = new AkavacheEntity ();
			await db.RemoveObjectAsync<FacebookUser> (Const.USER_AKAVACHE_KEY);

			await Navigation.PushModalAsync (new LoginPage ());
		}
		public PlacesPage ()
		{
			InitializeComponent ();
			_db = new AkavacheEntity ();
		}
		public PlacePage (int id)
		{
			InitializeComponent ();
			PlaceId = id;
			_db = new AkavacheEntity ();
		}
		public UserPage ()
		{
			InitializeComponent ();
			_db = new AkavacheEntity ();
		}
		public RankingPage ()
		{
			InitializeComponent ();
			_db = new AkavacheEntity ();
		}