Bug 37905: Use correct RFC3339 formatted date to the server

Bug 37905: Use correct RFC3339 formatted date to the server

This patch suggests to revert the previous attempt to fix this problem.
The date was using the client-side's tz and so the "last hour" was not
matching the one from the server.

With bug 37831 with simply need to pass a rfc3339-formatted date and the
filtering will be done as expected.

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>