Add pex for managing PostgreSQL extensions.

Library/Formula/pex.rb

@@ -0,0 +1,23 @@
+require "formula"
+
+class Pex < Formula
+  homepage "https://github.com/petere/pex"
+  url "https://github.com/petere/pex/archive/1.20140409.tar.gz"
+  sha1 "7cc652cd89bc6c6bf2488c8eb1ee91588053262a"
+
+  depends_on :postgresql
+
+  def install
+    system "make", "install", "prefix=#{prefix}", "mandir=#{man}"
+  end
+
+  def caveats; <<-EOS.undent
+    If installing for the first time, perform the following in order to setup the necessary directory structure:
+      pex init
+    EOS
+  end
+
+  test do
+    assert_match /share\/pex\/packages/, `pex --repo`.strip
+  end
+end