title: bundle install is not successful cannot install ffi 1.9.9 osx 10.9
body: <pre><code>bundle install  
  Fetching gem metadata from https://rubygems.org/...........  
  Fetching gem metadata from https://rubygems.org/..  
  Resolving dependencies...  
  Enter your password to install the bundled RubyGems to your system:   
  Using addressable (2.3.8)   
  Using sass (3.4.15)   
  Using sassy-maps (0.4.0)   
  Using breakpoint (2.5.0)   
  Using chunky_png (1.3.4)   
  Using coderay (1.1.0)   
  Using multi_json (1.11.1)   
  Using compass-core (1.0.3)   
  Using compass-import-once (1.0.5)   
  Using rb-fsevent (0.9.5)   
  Installing ffi (1.9.9)   
  Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension. 
  </code></pre>
  
  <blockquote>
    <p>/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb<br>
    mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/include/ruby.h  </p>
    
    <p>Gem files will remain installed in /Users/Moe/.bundler/tmp/8353/gems/ffi-1.9.9 for inspection.<br>
    Results logged to /Users/Moe/.bundler/tmp/8353/gems/ffi-1.9.9/ext/ffi_c/gem_make.out  </p>
    
    <p>An error occurred while installing ffi (1.9.9), and Bundler cannot continue.
    Make sure that <code>gem install ffi -v '1.9.9'</code> succeeds before bundling.  </p>
  </blockquote>