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/development/libraries/dssi/default.nix

@@ -1,5 +1,5 @@
 x@{builderDefsPackage
-  , ladspaH, jackaudio, liblo, alsaLib, qt4, libX11, libsndfile, libSM
+  , ladspaH, jack2, liblo, alsaLib, qt4, libX11, libsndfile, libSM
   , libsamplerate, libtool, autoconf, automake, xproto, libICE, pkgconfig
   , ...}:
 builderDefsPackage