un-hide the emacs-bug-tracker list on Savannah

[Glenn Morris]

Please could someone with the necessary privs (I think this is any
admin of the Savannah Emacs project) put the "emacs-bug-tracker" list
back on display in the Savannah web page that lists Emacs mailing lists:

http://savannah.gnu.org/mail/?group=emacs

It was previosuly hidden, see http://debbugs.gnu.org/2324, because it
wasn't being used at the time.

There are still some issues to work out, but it is being used now.

Thanks.