request to change priority of libg15daemon-client1 from extra to optional

[Giacomo A. Catenazzi]

Hello ftp-masters,

I've a request from mumble maintainer to raise the priority of
libg15daemon-client1 to optional, because of new dependencies.

As the maintainer of libg15daemon I've no problem on that.
If you agree, on next upload I'll also update the debian/control.

ciao
	cate