move extension to subdir in scaffold

edbob/scaffolds/edbob/+package+/extension/__init__.py_tmpl

@@ -0,0 +1,12 @@
+#!/usr/bin/env python
+
+"""
+``{{package}}.extension`` -- Schema Extension
+"""
+
+from edbob.db.extensions import Extension
+
+
+class {{package}}_extension(Extension):
+
+    name = '{{package}}'

edbob/scaffolds/edbob/+package+/extension/model.py_tmpl

@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 
 """
-``{{package}}.model`` -- Schema Definition
+``{{package}}.extension.model`` -- Schema Definition
 """
 
 from sqlalchemy import Column, Integer, String, ForeignKey

edbob/scaffolds/edbob/setup.py_tmpl

@@ -80,7 +80,7 @@ setup(
 {{package}} = {{package}}.commands:main
 
 [edbob.db.extensions]
-{{package}} = {{package}}:{{package}}_extension
+{{package}} = {{package}}.extension:{{package}}_extension
 
 [{{package}}.commands]
 initialize = {{package}}.commands:InitCommand