Improve 'settings' API functions so they don't require a session.

Seems way handier that way, sometimes.

rattail/db/api/settings.py

@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  Rattail -- Retail Software Framework
-#  Copyright © 2010-2014 Lance Edgar
+#  Copyright © 2010-2015 Lance Edgar
 #
 #  This file is part of Rattail.
 #
@@ -26,27 +26,37 @@ Settings API
 
 from __future__ import unicode_literals
 
-from .. import model
-
-
-__all__ = ['get_setting', 'save_setting']
+from rattail.db import Session, model
 
 
 def get_setting(session, name):
     """
     Returns a setting value from the database.
     """
+    local_session = False
+    if session is None:
+        session = Session()
+        local_session = True
     setting = session.query(model.Setting).get(name)
-    if setting:
-        return setting.value
+    value = None if setting is None else setting.value
+    if local_session:
+        session.close()
+    return value
 
 
 def save_setting(session, name, value):
     """
     Saves a setting to the database.
     """
+    local_session = False
+    if session is None:
+        session = Session()
+        local_session = True
     setting = session.query(model.Setting).get(name)
     if not setting:
         setting = model.Setting(name=name)
         session.add(setting)
     setting.value = value
+    if local_session:
+        session.commit()
+        session.close()