Add more files and lines when scaffolding (#1222)

* auto-generatr urls.py

* add mocks to moto/__init__.py and moto/backends.py

* add uri to urls.py

* change output of scaffold.py

scripts/template/lib/urls.py.j2

@@ -0,0 +1,9 @@
+from __future__ import unicode_literals
+from .responses import {{ service_class }}Response
+
+url_bases = [
+    "https?://{{ endpoint_prefix }}.(.+).amazonaws.com",
+]
+
+url_paths = {
+}