add protocol version, reset migrations, move db

oml/db.py

@@ -0,0 +1,27 @@
+from sqlalchemy.ext.mutable import Mutable
+
+class MutableDict(Mutable, dict):
+    @classmethod
+    def coerce(cls, key, value):
+        "Convert plain dictionaries to MutableDict."
+
+        if not isinstance(value, MutableDict):
+            if isinstance(value, dict):
+                return MutableDict(value)
+
+            # this call will raise ValueError
+            return Mutable.coerce(key, value)
+        else:
+            return value
+
+    def __setitem__(self, key, value):
+        "Detect dictionary set events and emit change events."
+
+        dict.__setitem__(self, key, value)
+        self.changed()
+
+    def __delitem__(self, key):
+        "Detect dictionary del events and emit change events."
+
+        dict.__delitem__(self, key)
+        self.changed()