Watch: Add optional integration with Watchman?

[andreynering]

Originally suggested by someone else on Reddit

[tylermmorton]

On this front I found https://github.com/sjansen/watchman -- it looks like a Go client that does exactly what was mentioned in the Reddit post. The project seems largely WIP and 3 years stale but according to status.md it at least has watch_list and watch_project implemented, which is the bulk of whats needed for Task.

Could we fork this project and and continue development of the API's we need under go-task/watchman?