Fix config schema error

Config schema validation still fails, because existing config values for the mustrevalidate, nocache, nostore & cookieextra options still need to be converted to booleans.

I added an update hook to convert existing config.

Automatically closed - issue fixed for 2 weeks with no activity.

Looks like the fix here somehow didn't make its way to the last release.. Can we have it released?

Looks like this was accidentally committed to the wrong branch. Thanks for reporting, I'll fix it.