aqbanking: Move sources into a common sources.nix

The upstream URLs unfortunately aren't canonical, so let's have a
sources.nix which contains the release IDs used by the upstream sites to
associate a version of a particular package.

We're then going to create an updater script which should update the
sources.nix from there on.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Cc: @cillianderoiste, @urkud

pkgs/development/libraries/aqbanking/libchipcard.nix

@@ -5,13 +5,13 @@ stdenv.mkDerivation rec {
   version = "5.0.4";
 
   src = let
-    releaseNum = 200; # Change this on update
-    qstring = "package=02&release=${toString releaseNum}&file=01";
+    inherit ((import ./sources.nix).libchipcard) sha256 releaseId;
+    qstring = "package=02&release=${releaseId}&file=01";
     mkURLs = map (base: "${base}/sites/download/download.php?${qstring}");
   in fetchurl {
     name = "${name}.tar.gz";
     urls = mkURLs [ "http://www.aquamaniac.de" "http://www2.aquamaniac.de" ];
-    sha256 = "0fj2h39ll4kiv28ch8qgzdbdbnzs8gl812qnm660bw89rynpjnnj";
+    inherit sha256;
   };
 
   nativeBuildInputs = [ pkgconfig ];