No longer assume problemNum is base 0 indexed.

This change has two commits, one of which is in the webapp project.

Test Plan:
Played around with the navigation and made sure things appeared as
expected.

Auditors: dylan
Remove STOPSHIPs for localstorage support.

Dylan mentioned that every browser we support has localStorage
support, so yippee!

Test Plan:
Comments only changes, so crossed fingers.

Auditors: dylan