Increase default STS_MAX_AGE from 30 days to 1 year to allow inclusion into HSTS preload list

Firefox requires that any built-in HSTS preloads have a max-age of at least 18 weeks (10886400 seconds), as per https://wiki.mozilla.org/Privacy/Features/HSTS_Preload_List. Since that's already over 4 months, make the default 1 year (31536000 seconds).

If this ever becomes a problem, a max-age of 0 can be used as a knock-out entry to override any built-in or existing browser settings.