Script the download of multiple CI job logs

An initial implementation of #40

To do

• Ability to provide pipeline have the script crawl all associated jobs.
  • or commit IDs => #42
• Ability (or default) to skip skippped jobs. Example: gemnasium/-/pipelines/1009911119; Produced logs of *-skipped-*.log files, which contain only the # jobname header.
• some kind of progress indicator/logging

Example output & filenames (as of ac6d5ecc)

Downloading CI-5218726495j-failed.log ...
Downloading CI-1025018388p-5218726633j-skipped.log ...
Downloading CI-1025018388p-5218726631j-skipped.log ...
Downloading CI-1025018388p-5218726626j-success.log ...