Fixed bug : local time lost

Changed behaviour for internal time storage. Now we only use GMT, for
display and storage, and translate timestamps so that they are GMT local
time (e.g. 13:37 GMT+2 will be 13:37 GMT internally).

Signed-off-by: pralonga <aurelien.pralong@gmail.com>
Release 1.5 preparation
Signed-off-by: pralonga <aurelien.pralong@gmail.com>