example-master, log information about environment

example-master is mostly for testing, log the options loaded, and
information about process identity (master/worker/id/pid).
Prefer cluster to size in command line and config

The name makes more sense when used on a command line, and with
strong-supervisor. Size is still supported.

See SLN-752
Note existence of strong-supervisor in README
Merge pull request #33 from strongloop/feature/usability-tweaks

Feature/usability tweaks