New Strategy options

This pull request should increase the compatibility of the Strategy with different LDAP servers (i.e.: Windows Active Directory, OpenLDAP on Linux/Sun Solaris).

- Options added to Strategy creation:
  - authOnly: if true only the bind against the LDAP is done, otherwise also the search will be executed.
  - authMode: 0 for the Windows AD user definition (user name only), 1 for the OpenLDAP user definition (complete DN: user id + base DN).
  - uidTag: string representing the user id tag in the complete DN used as a user with authMode 1.
  - debug: if set to true, debug informations are printed to cmd (very usefull when interfacing new LDAP servers ;) ).
- Modified the code for Strategy accordingly to the added options.
- When defining a filter for the search, if the string '$uid$' is used inside the filter string, it will be replaced by the user id given for the authentication - i.e. we can use as a filter '(uid=$uid$)', which for instance will be translated in '(uid=user1)'.
- Added command line examples to access win* and *nix LDAP servers.

Regards,
Matteo