[Evolution-hackers] Minor API break in libebackend

[Matthew Barnes <mbarnes redhat com>]

In working on the create/delete remote folder API for collection
backends, I realized these backends are going to need something
equivalent to e_source_registry_authenticate().

e_source_registry_server_queue_auth_session() is a "fire and forget"
function in that the caller doesn't know when or even IF authentication
succeeds.  So I replaced it with the following functions:

  gboolean  e_source_registry_server_authenticate_sync
                                (ESourceRegistryServer *server,
                                 EAuthenticationSession *session,
                                 GCancellable *cancellable,
                                 GError **error);

  void      e_source_registry_server_authenticate
                                (ESourceRegistryServer *server,
                                 EAuthenticationSession *session,
                                 GCancellable *cancellable,
                                 GASyncReadyCallback callback,
                                 gpointer user_data);

  gboolean  e_source_registry_server_authenticate_finish
                                (ESourceRegistryServer *server,
                                 GAsyncResult *result,
                                 GError **error);

I also pushed commits to EWS and MAPI to cope with the change.

I figure since this new account-mgmt API hasn't seen a stable release
yet, and since this particular change should only affect us, I'm not
bothering with deprecations yet but I did bump the libebackend soname.

Anyway, just a heads up.

Matt