Unify means of specifying environment to --env=<environment> 

*If omitted & param is optional, defaults to 'dev'
*Supports arbitrary environment --env=foobar
*Deprecates support for fhc restart appId live or fhc restart appId --live - still supported but prints a warning

There'll be more work for FHC when things with dev/live specific endpoints (hosts developmentHost, env's devValue) are updated - deemed not in scope here.

Previous P/R & discussion here:
#92