Don't hide errors in pupa_settings
Update load shim to use the loader interface

 This will let us scan sys.path to ensure we can load the module.

 Rather then kick off a load to sys.modules with the loader, we can
 simply ignore it and kick off an import if we've got a hit. Since we're
 only using Python 3.3+, we can be sure the standard import machinery is
 using importlib / PEP 302.
Restore the default print message.

 Thanks, @jpmckinney