Updated update call to inlcude a callback specifically for tests and added test for update call
True async ajax call if a callback is specified in the update method call and updated its test
Function to poll ready state a fixed number of times
Used JSON.stringify to convert dataset ids array into string
Tests for merges
Updated merge function with expected dataset_ids param
Check expected args to ajax call
Upated join function to take in ids and not actual datasets
Added mandatory callback to join call and call it with an instance of the joined dataset
Tests for join function and mock data