Bumped to futures 0.3 / tokio 0.2 and rust 2018 edition#3

Closed

ryanpresciense wants to merge 8 commits intolibrespot-org:masterfrom ryanpresciense:master

+716-562

Commits on Mar 26, 2020

Upgrading to new tokio / futures and rust 2018 edition.
ryansroberts
committed

Commits on Apr 1, 2020

Commits on Apr 3, 2020

Edge triggered, so must poll recv until done, oops
ryansroberts
committed