-Fix: multi-threading with imports.

Somehow we had a different object in the modules list, that way imported
modules from <registry 1> would be registered to <registry 2> .. and
could then not be found in <registry 1>.

We now ensure that the main plugin var on the guruapid module is set to
the Registry loader calling load.. this way we enforce plugins that use
'from guruapid import plugin' to ALWAYS register to the right location.