Use common licence attributes from lib/licenses.nix

Many (less easily automatically converted) old-style strings
remain.

Where there was any possible ambiguity about the exact version or
variant intended, nothing was changed. IANAL, nor a search robot.

Use `with stdenv.lib` wherever it makes sense.

pkgs/tools/networking/wicd/default.nix

@@ -100,7 +100,7 @@ stdenv.mkDerivation rec {
     echo "wpa2-ttls" >> "$out/etc/encryption/templates/active"
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     homepage = http://wicd.net/;
     description = "A wiredless and wired network manager";
     longDescription=''
@@ -112,7 +112,7 @@ stdenv.mkDerivation rec {
       encryption types, such as WPA and WEP. Wicd will automatically
       connect at startup to any preferred network within range.
     '';
-    maintainers = [ stdenv.lib.maintainers.roconnor ];
-    license="GPLv2";
+    maintainers = [ maintainers.roconnor ];
+    license = with licenses; gpl2;
   };
 }