This PR fixes a flakey test where we did not wait on the check
status to actually become failing (go too fast and you just get
a pending check).
Instead add a helper for waiting on any check in the alloc to become
the state we are looking for.
This PR adds some NSD check status output to the CLI.
1. The 'nomad alloc status' command produces nsd check summary output (if present)
2. The 'nomad alloc checks' sub-command is added to produce complete nsd check output (if present)
This PR is the first of several for cleaning up warnings, and refactoring
bits of code in the command package. First pass is over acl_ files and
gets some helpers in place.
