Move to Pony version 0.30.0 or 0.31.0 when feasible

[slfritchie]

Is this a bug, feature request, or feedback?

Bug

What is the current behavior?

Current behavior of Wallaroo + Pony 0.29.0 + omitting use of the --ponynoblock flag is intermittent SIGSEGV crashes caused by the Pony runtime's cycle detector.

What is the expected behavior?

Wallaroo should avoid crashing, regardless of use of --ponynoblock.

What OS and version of Wallaroo are you using?

Ubuntu Xenial/18.04 LTS + Wallaroo @ commit cd256a2

Steps to reproduce?

I've been running 2 or 3 worker Wallaroo clusters with the passthrough or aloc_passthrough app under moderate workload on 2 vCPU VM with a single data sending process, see https://gist.github.com/slfritchie/860ebbced40b94e02d221771af442e4f for setup-and-run script.