add JSON utility functions, cleanup, commented out simulator workaround

Assorted changes arising from merging simulator branch in ngrm repo:
* New JSON utility functions for doubles and bools
* Add a commented out workaround for simulator race in job module.  It's not appropriate to enable but as Stephen felt he needed it, I wanted to include it for now until race is addressed properly.
* (cleanup) Drop scheduler code in wreck subdir that should not be part of flux-core