pmctl: add a control CLI to pm and supervisor

Its supports both control of the process manager, and control of the
processes it manages, including most of the features of supervisor's
runctl.
deps: update to strong-supervisor@0.3.3

0.3.3 is the first release to use strong-control-channel@0.2.2, which
is required for correct control channel operation.
test: update strong-build to 0.2.x
test: don't pipe stdout, or collect stderr

We don't use stderr, and piping stdout is noisy and unnecessary.
test: objects-start/stop doesn't work without a license

Disable that part of the test in the absence of a license.
pmctl: fix missing argument --config in usage

The --config option was missing it's CFG argument.
package: document usage and configuration
package: add keywords for npm search
package: update pm-install usage in README