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/mhwaveedit/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, SDL , alsaLib, gtk, jackaudio, ladspaH
+{ stdenv, fetchurl, SDL , alsaLib, gtk, jack2, ladspaH
 , ladspaPlugins, libsamplerate, libsndfile, pkgconfig, pulseaudio }:
 
 stdenv.mkDerivation  rec {
@@ -11,7 +11,7 @@ stdenv.mkDerivation  rec {
   };
 
   buildInputs =
-   [ SDL alsaLib gtk jackaudio ladspaH libsamplerate libsndfile
+   [ SDL alsaLib gtk jack2 ladspaH libsamplerate libsndfile
      pkgconfig pulseaudio
    ];