Set Creation: Saving of Progress

[alexrcabral]

Any action which would take a user away from the page should save the current progress (e.g. clicking to go back to dashboard should save your progress before taking you away from problem set creation, clicking another problem should save your progress on the current problem before moving to the selected problem). 

On top of this, every 15 seconds it should autosave to prevent loss of work. 

Acceptance Criteria

Given that I'm a user on the problem creation page, my work should be saved every 15 seconds that I've been editing a problem. My progress should also be saved if I move to a new problem, or take any actions that would take me away from the problem set creation page (e.g. clicking to go back to dashboard). 

[abaranowska1]

Tested with success

• Given that I'm a user on the problem creation page, my work is saved every 15 seconds that I've been editing a problem.
• My progress is saved when I click Mathshare logo to go back to dashboard, click back button, change the browser tab, click on an empty space