multipath_tools: Rename to multipath-tools

See http://nixos.org/nixpkgs/manual/#sec-package-naming

I've added an alias for multipath_tools to make sure that we don't break
existing configurations referencing the old name.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

pkgs/development/python-modules/blivet/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchFromGitHub, buildPythonPackage, pykickstart, pyparted, pyblock
-, pyudev, six, libselinux, cryptsetup, multipath_tools, lsof, utillinux
+, pyudev, six, libselinux, cryptsetup, multipath-tools, lsof, utillinux
 }:
 
 let
@@ -19,7 +19,7 @@ in buildPythonPackage rec {
 
   postPatch = ''
     sed -i \
-      -e 's|"multipath"|"${multipath_tools}/sbin/multipath"|' \
+      -e 's|"multipath"|"${multipath-tools}/sbin/multipath"|' \
       -e '/^def set_friendly_names/a \    return False' \
       blivet/devicelibs/mpath.py
     sed -i -e '/"wipefs"/ {