Fix to a bug where an ARMI application could not call (#593)

`armi.configure(app, permissive=True)`. This error is
due to fact that the type check for the application that
is passed in would never be equal to the type of the base
ARMI app class. This now checks if the application passed
in is instead an instance of the ARMI app.

armi/__init__.py

@@ -306,7 +306,7 @@ def configure(app: Optional[apps.App] = None, permissive=False):
     app = app or apps.App()
 
     if _app is not None:
-        if permissive and type(_app) is type(app):
+        if permissive and isinstance(app, apps.App):
             return
         else:
             raise RuntimeError(