Allow defer to external config

This commit updates the bootstrapping file to remove deprecated
functionality and adds the new "--use-json" (alias: -x) flag, which
prompts the engine to defer to external JSON configuration files used
for development.  It is *NOT* recommended to use this flag during
production!

NOTICE:  when using this new flag, the Arpk::Config reference will no
longer be an instance of Arpk::Database, but an instance of ObjGraph.
As such, this will allow read-write functionality to in-memory
configuration data at runtime (the file itself will not change).

This commit also removes the Environment reference from the Arpk
namespace, as the feature was never fully used and has been largely
replaced by the Arpk::Config database reference.