bump finagle and util to 6.22.0

this bumps finagle and util to 6.22.0 and fixes the finagle-mysql usage which has changed since 6.12.2.

there aren't any published 2.9 artifacts for finagle and util 6.22.0 so this breaks that build.

https://travis-ci.org/dschobel/storehaus/builds/43419185