treewide: simplify rev/repo arguments in src

+ use fetchFromGithub where possible

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

@@ -1,6 +1,6 @@
 { stdenv
 , buildPythonPackage
-, fetchgit
+, fetchFromGitHub
 , pyramid
 , hawkauthlib
 , tokenlib
@@ -8,11 +8,12 @@
 }:
 
 buildPythonPackage rec {
-  pname = "pyramidhawkauth";
+  pname = "pyramid_hawkauth";
   version = "0.1.0";
 
-  src = fetchgit {
-    url = "https://github.com/mozilla-services/pyramid_hawkauth.git";
+  src = fetchFromGitHub {
+    owner = "mozilla-services";
+    repo = pname;
     rev = "refs/tags/v${version}";
     sha256 = "038ign7qlavlmvrhb2y8bygbxvy4j7bx2k1zg0i3wblg2ja50w7h";
   };