Support GitLab.com repositories, add content searching, improve performance by cloning to memory, add docker support

[codeEmitter]

Hi @michenriksen. The GitLab Red Team has made some feature enhancement to gitrob you may or may not be interested in:

• Support for GitLab users and groups
• Support for multiple modes of execution including content search
  • Mode 1 - Default mode to match on file signatures
  • Mode 2 - Match on file signatures then content signatures to constitute a result.
  • Mode 3 - Match on content signatures only without file signature matches.
• Support for in-memory repository clones, which can result in significantly faster analysis times depending on your hardware.
• File signatures for Google Cloud Platform credentials
• Content signatures similar to trufflehog.

More details are in the readme.md in terms of usage. If this PR is something you're interested in, we'll probably need to update some dependency paths to support the current forked version before merging. Thanks for your consideration!