Clean up some test warnings.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fix log test to work on other people's timezones.

Oops.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Remove a test leak, and extra helper key check.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Make the target block time and horizon for testnet 60x shorter.

Easier for testing, plus more fun!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>