Adds a new UserDB option, "from_plain" that when set to 1 along with the
promote option will cause Interchange to assume that all current passwords are
plain text unless they meet the criteria of the new encryption scheme.  Note
that this is not perfect as it is possible for plain text passwords to appear to
Interchange as if they are already encrypted, and if Interchange thinks they
look like the encryption scheme that you're promoting to, either by password
length, or by a regexp match in the case of bcrypt then Itnerchange will not
promote the password and assuming it is already encrypted the login will fail.
While not a perfect solution to the issue of gracefully promoting passwords from
plain text this is a "better than nothing" approach.

To use this option, specify the following in your catalog.cfg in addition to the
other option changes necessary to convert to encrypted passwords:

    UserDB foo promote 1
    UserDB foo from_plain 1

Note that it is not recommended that you simply set this and forget in order to
promote plain text passwords.  Having plain text passwords in your DB is now
considered extremely bad practice and if you simply attempt to promote them via
this method you will still have a large number of plain text passwords in your
db for some time to come.  It is instead recommended that you use this method in
conjunction with another method to convert all remaining passwords as quickly as
possible.  This is simply in place as a means to help you avoid downtime of your
site while the passwords are being promoted.