Move AmazonWebServicesFormula to formula_specialties

Enough formulae in core depend on this, pull it in here.
When multi-repo support lands, perhaps we could set up Homebrew-AWS.

Library/Homebrew/formula_specialties.rb

@@ -14,3 +14,41 @@ class GithubGistFormula < ScriptFileFormula
     @version=File.basename(File.dirname(url))[0,6]
   end
 end
+
+# This formula serves as the base class for several very similar
+# formulae for Amazon Web Services related tools.
+class AmazonWebServicesFormula < Formula
+  # Use this method to peform a standard install for Java-based tools,
+  # keeping the .jars out of HOMEBREW_PREFIX/lib
+  def standard_install
+    rm Dir['bin/*.cmd'] # Remove Windows versions
+    prefix.install "bin"
+    # Put the .jars in prefix/jars/lib, which isn't linked to the Cellar
+    # This will prevent conflicts with other versions of these jars.
+    (prefix+'jars').install 'lib'
+    (prefix+'jars/bin').make_symlink '../bin'
+  end
+
+  # Use this method to generate standard caveats.
+  def standard_instructions var_name, var_value=prefix+'jars'
+    <<-EOS.undent
+      Before you can use these tools you must export some variables to your $SHELL
+      and download your X.509 certificate and private key from Amazon Web Services.
+
+      Your certificate and private key are available at:
+      http://aws-portal.amazon.com/gp/aws/developer/account/index.html?action=access-key
+
+      Download two ".pem" files, one starting with `pk-`, and one starting with `cert-`.
+      You need to put both into a folder in your home directory, `~/.ec2`.
+
+      To export the needed variables, add them to your dotfiles.
+       * On Bash, add them to `~/.bash_profile`.
+       * On Zsh, add them to `~/.zprofile` instead.
+
+      export JAVA_HOME="$(/usr/libexec/java_home)"
+      export EC2_PRIVATE_KEY="$(/bin/ls $HOME/.ec2/pk-*.pem)"
+      export EC2_CERT="$(/bin/ls $HOME/.ec2/cert-*.pem)"
+      export #{var_name}="#{var_value}"
+    EOS
+  end
+end