Launch all nodes in READY state

Currently the launcher thread executes one node in READY state per cycle. Then it sleeps sleep_time seconds until it launches another node in READY state, if available. Thus, if there are 10 nodes in READY state one has to wait minimum 5 minutes for them to be launched (plus execution time if interactive and time for submission to SLURM is batch.

The algorithm should be changed such that all READY nodes are processed before going to sleep.