rename save -> create (and save==update)

Author: dakra

atomx/models.py

@@ -55,7 +55,7 @@ def _dirty_json(self):
     def json(self):
         return self._attributes
 
-    def save(self, session=None):
+    def create(self, session=None):
         session = session or self.session
         if not session:
             raise NoSessionError
@@ -64,6 +64,9 @@ def save(self, session=None):
         return self
 
     def update(self, session=None):
+        return self.save(session)
+
+    def save(self, session=None):
         session = session or self.session
         if not session:
             raise NoSessionError