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/qsynth/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, alsaLib, fluidsynth, jackaudio, qt4 }:
+{ stdenv, fetchurl, alsaLib, fluidsynth, jack2, qt4 }:
 
 stdenv.mkDerivation  rec {
   name = "qsynth-${version}";
@@ -9,7 +9,7 @@ stdenv.mkDerivation  rec {
     sha256 = "0wmq61cq93x2l00xwr871373mj3dwamz1dg6v62x7s8m1612ndrw";
   };
 
-  buildInputs = [ alsaLib fluidsynth jackaudio qt4 ];
+  buildInputs = [ alsaLib fluidsynth jack2 qt4 ];
 
   meta = with stdenv.lib; {
     description = "Fluidsynth GUI";