New package structure for the version 2 of the public api.

Start building up the validators required for post notificaiton.
The app/v2/errors.py is a rough sketch, will be passed a code, the error can look up the message and link for the error message.

app/v2/notifications/__init__.py

@@ -0,0 +1,7 @@
+from flask import Blueprint
+
+from app.v2.errors import register_errors
+
+notification_blueprint = Blueprint(__name__, __name__, url_prefix='/v2/notifications')
+
+register_errors(notification_blueprint)