Pulled in Java simulator support changes from 'develop' to better support...

Pulled in Java simulator support changes from 'develop' to better support starting/stopping X number of simulators (via NUM_SIMS environment variable, defaults to 2).
Merged in some Makefile cleanup from 'develop' better integrate json-c into development builds.
Added explicit json_install/json_uninstall tasks which are NOT tied into default Make install/uninstall tasks for the lib.