Add CryptoUtils wrappers for PBKDF2, SHA-1
Added SASL SCRAM-SHA-1 support.
Moved José's SCRAM implementation to the right place.
Rework SCRAM-SHA-1 support into current form.

Also added an HMAC-SHA-1 wrapper. Mostly the changes were quite simple, though
quite a few lines were touched.

This is untested, and has no tests yet - the existing tests will not trigger
the code.