Add password rotation restrictions

1/ run phpunit tests 2/ disable password rotation restrictions and try changing password via change pw page and pw reset (regression testing only) 3/ enable password rotation restriction (note that current password at the time of enabling is not tracker, I was bitten by this a few times thinking it does not work) 4/ try changing own password - verify restriction is enforced 5/ try resetting own password - verify restriction is enforced 6/ signup as new user via email and verify the first password is tracked too Places where password rotation is tracked and enforced: forgotten password change own password user signup Places where password rotation is NOT tracked and enforced: using advanced user edit form - for security reasons nobody else should get any indication what was your password before! user upload and automatic creation of passwords web services