[s4] Passwords work

[Matthias Dieter Wallnöfer]

In my personal repo under the "passwords" branch I finally completed the 
work regarding the LDAP password handling for s4.
I spoke already once to abartlet and he gave me some suggestions which I 
implemented (eg the additional controls - one for returning password 
policy information, one for allowing password changes/sets only through 
hashes - which bypasses some checks). In addition I have finished a 
python test suite (passwords.py) which shows the password handling 
capabilities directly over LDAP (indirectly we have it already through 
the SAMR password tests).

I tried to match the LDAP result codes of Windows as much as possible. I 
was stuck to run the my test script against Windows since it requires a 
LDAPS over SSL connection and I didn't know how to get this working on 
s4 as a client. So I generated analogous test requests with an LDAP 
client on the server (where I managed to prepare and install the 
certificate) and compared the results.

Greets,
Matthias