Removed custom timeslot and duration to make a reservation on OAR.

Removed custom timeslot and duration to make a reservation on OAR.
Now using SFA format with leases to make reservation.
Refactored code: Shrinked LaunchExperimentOnOAR and created new functions
to create the request, process the walltime, configure the experiment
and launch senslab experiment using the java lib.
Launching an experiment asap still possible, although this is not supposed
to be used in SFA.