"mount blob" was the only feature we didn't handle.
We don't fully support it yet because we don't have access control
support, but at least handle it and return something sane to remain
compliant.
This adds a new --json flag to the compliance subcommand, which
will output the compliance test results as minified JSON to stdout.
Also a few other small additions:
- Exit 1 if compliance tests fail
- Use random port for test server using freeport library (added)
Signed-off-by: Josh Dolitsky <393494+jdolitsky@users.noreply.github.com>