External command "brew audit <formula>"

"brew audit <formula>" will check the given formula for a couple of
known issues:
  * Is an explicit mirror being used for a SourceForge download path?
  * Is the commented-out cmake support present?

Library/Contributions/examples/brew-audit.rb

@@ -0,0 +1,31 @@
+require 'formula'
+require 'utils'
+
+def ff
+  if ARGV.named.empty?
+    stuff = []
+    Formulary.read_all do |name,k|
+      stuff << Formula.factory(name)
+    end
+    return stuff
+  else
+    return ARGV.formulae
+  end
+end
+
+ff.each do |f|
+  problems = []
+  unless `grep "# depends_on 'cmake'" "#{f.path}"`.strip.empty?
+    problems << " * Commented cmake support still in #{f.name}"
+  end
+
+  unless `grep "\?use_mirror=" "#{f.path}"`.strip.empty?
+    problems << " * Remove 'use_mirror' from url for #{f.name}"
+  end
+
+  unless problems.empty?
+    puts "#{f.name}:"
+    puts problems * '\n'
+    puts
+  end
+end