Fix verification from generated keys

I was finding when generating keys (2048, '10001') that I'd end up with n.bitLength() = 2047.
The signature would accordingly have 2047 bits, so the test in verifyPSS failed - and is wrong I think.
So I moved it so it compares actual bit length of hash to n's bit length.
Also, relax the test so it passes as long as n has enough bits to cover the hash (but feel free to disagree with this if you like).

Also updated jsbn to latest.