Rename blocks => structure and add display_full_screen and exit_url fields.
Rename blocks => structure and add display_full_screen and exit_url fields.

CenterForOpenScience/lookit-api,pattisdr/lookit-api,CenterForOpenScience/lookit-api,CenterForOpenScience/lookit-api,pattisdr/lookit-api,pattisdr/lookit-api