echoprint-codegen: style nit-pick

Formula/echoprint-codegen.rb

@@ -1,14 +1,16 @@
 require 'formula'
 
 class EchoprintCodegen < Formula
-  head 'https://github.com/echonest/echoprint-codegen.git'
   homepage 'http://echoprint.me'
+  head 'https://github.com/echonest/echoprint-codegen.git'
 
   depends_on 'ffmpeg'
   depends_on 'taglib'
   depends_on 'boost'
 
   def install
-    system "cd src; PREFIX=#{prefix} make install"
+    cd 'src' do
+      system "make", "install", "PREFIX=#{prefix}"
+    end
   end
 end