Updated createEntity

Two updates:

- Updated the callback function to align with the the callback being returned by fetch(). Previously, only two params were being handled by the callback function but three were being passed by fetch().

- Updated the okToSave var to accept errorMsg === 'cannot fetch entity, no name specified'. This allows createEntity to succeed even if no 'name' property is passed to it. Previously, the fetch() call was blocking creation of entities that did not have a name specified.