Implement support for password history functionality.  The password history can
be maintained either based on the number of previous passwords to remember
(e.g., a user cannot re-use any of his/her last five passwords), or the length
of time the previous passwords have been retained (e.g., a user cannot re-use
any password he/she has had within the last 365 days), or both.

This commit also updates the manage-account tool so that it supports a public
option for displaying the password history state values, and a hidden option
for clearing a user's password history state.

OpenDS Issue Number:  339