Updated url, version, and sha256 references

1. Updated homepage, url, and head to refer to GitHub rather than coin-or.org
2. Updated version reference to most recent (2.11.4)
3. Updated sha256 for appropriate version (pending)

Changes related to the issue discussed at coin-or/CoinUtils#151

coinutils.rb

@@ -1,8 +1,10 @@
 class Coinutils < Formula
   desc "Utilities used by other Coin-OR projects"
-  homepage "https://projects.coin-or.org/CoinUtils"
-  url "https://www.coin-or.org/download/pkgsource/CoinUtils/CoinUtils-2.11.3.tgz"
-  sha256 "b5f904da40a9f1525f6d09105b599f7a8d95dd079e81b974ad0e0ffef1413dbc"
+  homepage "https://github.com/coin-or/CoinUtils"
+  url "https://github.com/coin-or/CoinUtils/archive/releases/2.11.4.tar.gz"
+  sha256 ""
+  head "https://github.com/coin-or/CoinUtils/tree/releases/2.11.4/CoinUtils"
+  revision 1
 
   option "with-glpk", "Build with support for reading AMPL/GMPL models"