Visualization bug correction

Visualization module impacted: stacked, stackedsolar, zoom,
dailyhistogram.
This change avoid bargraph to display wrong values in the month and
annual view.
Realtime visualisation when not logged in

According to feed_controller.php, data.json
(get_data(feedid,start,end,dp)) and timevalue.json
(get_timevalue_seconds(feedid)) are both usable in public or user mode.
By removing the apikey parameter from the 2 data.json requests, the
realtime graph is available with or without being logged in.
It's more comfortable than editing manualy the dashboards to add the
read apikey to make them visible.
Merge pull request #235 from OlivierNoname/master

Visualisation bug correction