plugins: Add crosslink plugin

[jayvdb]

Reviewers Checklist

• [ ] Appropriate logging is done.
• [ ] Appropriate error responses.
• [ ] Handle every possible exception.
• [ ] Make sure there is a docstring in the command functions. Hint: Lookout for botcmd and re_botcmd decorators.
• [ ] See that 100% coverage is there.
• [ ] See to it that mocking is not done where it is not necessary.

[meetmangukiya]

@gitmate-bot rebase

[gitmate-bot]

Hey! This pull request is being rebased automatically. Please DO NOT push while rebase is in progress or your changes would be lost!

[gitmate-bot]

Automated rebase failed! Please rebase your pull request manually via the command line.

Error: Command '['git', 'clone', '--depth', '1', 'rebase', '/tmp/tmpibsjp9gq']' returned non-zero exit status 128.

[jayvdb]

@gitmate-bot rebase

[gitmate-bot]

Hey! I'm GitMate.io! This pull request is being rebased automatically. Please DO NOT push while rebase is in progress or your changes would be lost permanently :warning:

[gitmate-bot]

Automated rebase with GitMate.io was successful! :tada: