Drop deprecated functions add/add_s

[phillipod]

Drop deprecated API's add/add_s

Quoting quanah in #13,

Hm, this seems somewhat broken overall. add/add_s are part of the deprecated OpenLDAP API, and no longer available. The new fuctions are ldap_add_ext and ldap_add_ext_s, which both take dn, attrs, sctrls, cctrls. (I know the Net::LDAPapi code uses them behind the scenes). Overall, I'm fine with the following:

If we move to Net::LDAPapi version 3.1.x, we can change the API however we want. The original concept was to have parity with the underlying C API. Both Mozilla and OpenLDAP's C API's support add_ext(_s). I'd like to see the Net::LDAPapi code remove the deprecated functions, and then we can fix the function documentation to match the correct current C API functions.