Smarter resume

[mgermain]

• [x] Also make sure that the jobs are appended properly to jobs_id.txt when we resume.
• [x] Allow using both path and Batch UID to resume jobs.
• [x] When we resume a job we should append a "##### RESUMING COMMAND #####" to the output file and then append the rest instead of overriding.
• [ ] Considering we have the jobs id logged in jobs_id.txt, when we resume we should verify that they are not still running and if they do ask for a confirmation of the resume. Or even better refuse the resume. If the user want to resume he'll have to kill what is running. The possibility of adding worker a running batch should be in a different function.
• [ ] Do not allow to resume when there are 0 commands left to run
• [ ] Make the info when you launch or resume jobs more concise. Just say x commands splitted in y jobs. Tell the number of jobs actually launched. Maybe tell the # of job resumed.