make import rqjob_register into module scope

dcor_shared/__init__.py

@@ -6,5 +6,5 @@
 from .dcinst import get_dc_instance
 from .mime import DC_MIME_TYPES, VALID_FORMATS
 from . import paths
-from .rqjob import RQJob
+from .rqjob import RQJob, rqjob_register
 from ._version import version as __version__