Add mining endpoint to Node API

[dagonharett]

Feature request: add a "Mining Endpoint" to the Node API, that could be used to retrieve the stats currently available on the Mining tab of the TUI. Would also be handy to get this into grin client.

Currently, when running grin in headless mode, there is no way to retrieve the mining statistics such as the connected workers.

[quentinlesceller]

That would be indeed a nice feature. That could implemented in the Node API v2 (probably owner side). I'm labelling this as "help wanted" this is definitely an easy first pull request to start working on Grin.

[ndcroos]

Hello, I'd like to work on this issue.

[quentinlesceller]

Sure @ndcroos you don't need permission. Just submit a pull request :).