update to opam-0.7.3

Library/Formula/opam.rb

@@ -2,11 +2,10 @@
 
 class Opam < Formula
   homepage 'https://github.com/OCamlPro/opam'
-  url 'https://github.com/OCamlPro/opam/tarball/0.7.2'
-  sha1 '7bf09bed5be8628ea853173bfca2e3b85190de65'
+  url 'https://github.com/OCamlPro/opam/tarball/0.7.3'
+  sha1 'ef2b8e8bb36d554315b56fd866688704577db053'
 
   depends_on "objective-caml"
-  depends_on "wget"
 
   def install
     system "./configure", "--prefix=#{prefix}"
@@ -19,14 +18,16 @@ def test
   end
 
   def caveats; <<-EOS.undent
-    opam uses ~/.opam by default to install packages, you need to init package
-    database first by running:
+    OPAM uses ~/.opam by default to install packages, so you need to initialize
+    the package database first by running (as a normal user):
 
-      opam init
+    $  opam init
 
-    and add the following line to ~/.profile to initialize opam environment:
+    and add the following line to ~/.profile to initialize the environment:
 
-      eval `opam config -env`
+    $  eval `opam config -env`
+
+    Documentation and tutorials are available at http://opam.ocamlpro.com
     EOS
   end
 end