Rewrite: Trello CLI 1.0

[mheap]

Trello CLI has been rebuilt from the ground up using the oclif CLI framework. This allows us to write unit tests for commands and ensure that things are working as expected.

Release highlights:

• Ability to write unit tests for commands
• Additional output formats (--format=(default|silent|json|csv))
• Nested subcommands e.g. card:create, list:create
• All dependencies packaged independently
• Releases controlled using changesets