Added support for Generic Tags.  Tags can be applied to Node, Site, Slice, Sliver.  Adjusted relation_name for SliceTags to not conflict with generic tag.
diff --git a/planetstack/core/models/__init__.py b/planetstack/core/models/__init__.py
index 4f8bd85..4e6cc83 100644
--- a/planetstack/core/models/__init__.py
+++ b/planetstack/core/models/__init__.py
@@ -1,5 +1,6 @@
 from .plcorebase import PlCoreBase
 from .deployment import Deployment
+from .tag import Tag
 from .site import Site
 from .site import SitePrivilege
 from .image import Image