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/sonic-visualiser/default.nix

@@ -1,6 +1,6 @@
 # TODO add plugins having various licenses, see http://www.vamp-plugins.org/download.html
 
-{ stdenv, fetchurl, alsaLib, bzip2, fftw, jackaudio, libX11, liblo
+{ stdenv, fetchurl, alsaLib, bzip2, fftw, jack2, libX11, liblo
 , libmad, libogg, librdf, librdf_raptor, librdf_rasqal, libsamplerate
 , libsndfile, pkgconfig, pulseaudio, qt5, redland
 , rubberband, serd, sord, vampSDK
@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
       sord
       pkgconfig
       # optional
-      jackaudio
+      jack2
       # portaudio
       pulseaudio
       libmad