mod_http_oauth2: Shorten default token validity periods
With refresh tokens, short lifetime for access tokens is not a problem.
The arbitrary choice of one hour seems reasonable. RFC 6749 has it as
example value.
One week for refresh tokens matching the default archive retention
period. This means that a client that remains unused for one week will
have to sign in again. An actively used client will continually push
that forward with each used refresh token.