Don't use "with licenses;" for single licences

And don't use square brackets on such lines.

pkgs/applications/window-managers/awesome/default.nix

@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
   meta = with stdenv.lib; {
     description = "Highly configurable, dynamic window manager for X";
     homepage    = http://awesome.naquadah.org/;
-    license     = with licenses; gpl2Plus;
+    license     = licenses.gpl2Plus;
     maintainers = with maintainers; [ lovek323 ];
     platforms   = platforms.linux;
   };

pkgs/applications/window-managers/tabbed/default.nix

@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
   meta = with stdenv.lib; {
     homepage = http://tools.suckless.org/tabbed;
     description = "Simple generic tabbed fronted to xembed aware applications";
-    license = with licenses; mit;
+    license = licenses.mit;
     maintainers = with maintainers; [ viric ];
     platforms = with platforms; linux;
   };

pkgs/applications/window-managers/vwm/default.nix

@@ -25,7 +25,7 @@ stdenv.mkDerivation rec {
   meta = with stdenv.lib; {
     homepage = http://vwm.sourceforge.net/;
     description = "Dynamic window manager for the console";
-    license = with licenses; gpl2Plus;
+    license = licenses.gpl2Plus;
     maintainers = with maintainers; [ viric ];
     platforms = with platforms; linux;
   };