createData
    createData(instanceData, cid)
  
  Creates instance data given the serialized form of the data and
the url settings.
If url.createData is a function, that function will be called.  If url.createData is a
string, a request to that string will be made. If url is a string, a POST request is made to
url.
Parameters
- instanceData 
{Object}:The serialized data of the instance.
 - cid 
{Number}:A unique id that represents the instance that is being created.
 
Returns
 {Promise<Object>}: 
A promise that resolves to the newly created instance data.