Multi-instance, limit number, and add tests, warn on failed auth in region

[allenluce]

Multiple instances be now be given on the command line. The resulting output table contains the instance type as well.

If a particular region refuses auth the process continues (instead of bombing out).

I've added -n to limit the number of output items.

I've also added a few tests using Mocha and modified the main module to support them.

There's also more promisification done. As well as local'ing some vars and doing other refactors. This tests clean under node versions 6 through 12.