[WIP] re-implement Gaggle removing compile-time feature

[jeremyandrews]

• move Manager into a thread to provide coordination of Worker instances
• move Worker into a thread to coordinate with Manager instance
• allow configurations and control of Manager thread via Controller

TODO:

• allow both Manager and Worker thread on same goose instance
• implement actual Gaggle commands through Controller to allow configuring/starting/stopping Gaggle, and for collection of Metrics

[nathanielc]

What is the status of gaggle for the next release? We are using gaggle as of 0.16.4 and would also like to contribute to this project but do not want to have to branch off 0.16.4.

[jeremyandrews]

I've not had time to push this forward for a while, but am looking to clean it up and finish it relatively soon. Gaggle support is definitely going to be reworked in an async way and again part of future releases.

[jeremyandrews]

Closed in favor of #548