Use ISLE for testing/review environments

[dannylamb]

How can we make testing/reviewing easier so as to encourage it happening more?

If we can figure out how to clone or copy environments in ISLE, down to the level that we have the exact code and config needed to test a PR, we can greatly reduce the overhead involved in testing. Think about how much more likely we'll be to get someone to test if all they have to do is use isle-dc and with a make command they have an environment to test a PR. That would really open some doors.