SEC-2564: Deprecate all salted digest password encoding

[Rob Winch](https://jira.spring.io/secure/ViewProfile.jspa?name=rwinch) (Migrated from [SEC-2564](https://jira.spring.io/browse/SEC-2564?redirect=false)) said:

We should do this to indicate to users that these password storage mechanisms are no longer considered secure. We should also remove these references from the manual.
