* test: add script to run flux tests
* feat(flux): enable test capabilities in Flux controller
* feat(flux): add MergeFiltersRule
* build: bump existing Dockerfiles to go 1.15
* build: add flux tests to CI
* refactor: allow for overriding tcp.Mux logger
* build: upgrade to Flux v0.111.0
This commit adds tcp.Mux which multiplexes connections over TCP using
the first byte as the header byte. Users can listen to the muxer
using mux.Listen(hdr) and obtain a net.Listener.