Catch failed jobs, output recovery actions

Addresses #40 (closed)

I've only done the changes for the slurm backend (because I could test it easily), it will have to be implemented for HTCondor later.

In the batch part:

• Collect tasks for which some jobs fail
• Do not perform task finalization action if some jobs failed
• When everything is done running (completed or failed), print failed commands, give path to log files.
• Print a suggestion of command that the user can run to resubmit the failed jobs.
• Configure monitoring waiting time in the ini file
• Do hadd with -f option: when running once with --maxFiles 1 to check if everything is fine, and then running again using --distributed driver, the finalization will fail because the result files will already exist (avoids having to remove them every time).
• Catch SIGINT (CTRL+C) when jobs are being monitored, and ask the user if he wants to cancel the running jobs.

In the analysis module:

• Tell the user what finalization commands (i.e. hadd) to run once all jobs have finished successfully.
• Do not run postprocessing if any task failed.