jack: change package and attr names to 'jack1' and 'jack2'

Currently, we have a 'jack' package with attrname 'jack1d' and a
'jackdbus' package with attrname 'jackaudio'. Make it consistent 'jack1'
and 'jack2' in both package name and attrname.

This aligns the naming with what can be found on the JACK homepage.

Q: what's the difference between jack1 and jack2?
A: http://trac.jackaudio.org/wiki/Q_differenc_jack1_jack2

pkgs/applications/audio/qtractor/default.nix

@@ -1,4 +1,4 @@
-{ alsaLib, autoconf, automake, dssi, fetchurl, gtk, jackaudio
+{ alsaLib, autoconf, automake, dssi, fetchurl, gtk, jack2
 , ladspaH, ladspaPlugins, liblo, libmad, libsamplerate, libsndfile
 , libtool, libvorbis, pkgconfig, qt4, rubberband, stdenv }:
 
@@ -12,7 +12,7 @@ stdenv.mkDerivation rec {
   };
 
   buildInputs =
-    [ alsaLib autoconf automake dssi gtk jackaudio ladspaH
+    [ alsaLib autoconf automake dssi gtk jack2 ladspaH
       ladspaPlugins liblo libmad libsamplerate libsndfile libtool
       libvorbis pkgconfig qt4 rubberband
     ];