Use go1.4 instead of go-1.4 in derivation names. Closes #6243

I chose meta.branch because go 1.1 and 1.2 had this already.

pkgs/development/compilers/go/1.3.nix

@@ -103,6 +103,7 @@ stdenv.mkDerivation {
   setupHook = ./setup-hook.sh;
 
   meta = {
+    branch = "1.3";
     homepage = http://golang.org/;
     description = "The Go Programming language";
     license = "BSD";

pkgs/development/compilers/go/1.4.nix

@@ -98,6 +98,7 @@ stdenv.mkDerivation {
   setupHook = ./setup-hook.sh;
 
   meta = {
+    branch = "1.4";
     homepage = http://golang.org/;
     description = "The Go Programming language";
     license = "BSD";