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/linuxsampler/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchsvn, alsaLib, asio, autoconf, automake, bison
-, jackaudio, libgig, libsndfile, libtool, lv2, pkgconfig }:
+, jack2, libgig, libsndfile, libtool, lv2, pkgconfig }:
 
 stdenv.mkDerivation rec {
   name = "linuxsampler-svn-${version}";
@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
   '';
 
   buildInputs = [ 
-   alsaLib asio autoconf automake bison jackaudio libgig libsndfile
+   alsaLib asio autoconf automake bison jack2 libgig libsndfile
    libtool lv2 pkgconfig
   ];