Candidates no longer need to register / login to take a test

Till now, on receiving an invite to a challenge, a candidate had to register at CodeEval in order to take the test. From now on, candidates will not have to register. They will receive a one time use url (assuming it's a timed challenge) and there will be a submit form on that url which will allow the user to upload his / her solution. 

This should make the workflow much smoother.