Ldap connect() method improvements

[Emmanuel Lécharny]

Hi !

Stefan has committed some changes for the 
LdapNetworkConnection.connect() method. We had some NPE (fixed) and also 
were incapable to tell  what were the root causes of a connection 
failure. Typical reasons were :

o timeout

o SSL/TLS handshake error (with various root causes)


Stefan's commit are fixing those aspects.

Now, the method is 275 lines long, which makes it very difficult to 
maintain. I will move out some parts of it in separate private methods 
to make it clearer.


Thanks !