Also be nice an handle exceptions thrown by DAL.

SW-488: used tbb_freeze as a test routine for the new lcurun like execute_in_parallel_over_stations methods, which use the new execute_in_parallel methods

I am afraid that the 0Hz central frequency can be attributed to an integer
divided by a double.  This should at least remove the uncertainty.

SW-488: only use cep4 nodes where no datawriters are running, and ask politely for a minimum amount of nodes (not guaranteed)

SW-488: minor fixes, logging, and added a parameter 'min_nr_of_nodes' to get_cep4_available_cpu_nodes_sorted_ascending_by_load so we can always get at least a number of cpu nodes, even if they are under (too) heavy load

Also refactored some functions out of the TBB_Dipole clase since they are
not essential fot the object itself.

Task SW-560: Remove unnecessary bash -c from call, which provoked a syntax error. We still have to escape the bash variables in the remote script.

SW-561: removed setting/initializing of dipoleCalibrationDelay*. These are now filled in using python modules https://svn.astron.nl/LOFAR/branches/SW-488-Epic_TBB_ALERT/MAC/TBB/lib/tbb_caltables.py which are automagically called in the tbbservice after the datawriters finished