Add dynamic password infrastructure

["W. Michael Petullo" <mike flyn org>]

Some media sources (e.g., DAAP) support notifying a client that a password
is required at connection time. Since such sources are commonly detected
with protocols like DNS-SD, Grilo needs a mechanism to support handling
these password requests.

I have written series of patches to add a new
"grl_source_notify_authenticate" function which plugins can call when a
password is needed. The function, in turn, emits an "authenticate" signal
which the application should respond to by obtaining a password. The
application then provides the password back to the plugin by calling
the new "grl_daap_source_continue_with_password" function.

My patches are available at:

        https://bugzilla.gnome.org/show_bug.cgi?id=795840

-- 
Mike

:wq