title: Rails: json 1.7.5 bundle install issue
body: <p>When running bundle I get the following issue...</p>
  
  <blockquote>
    <p>Installing json (1.7.5) with native extensions
    Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native
    extension.</p>
  
  <pre><code>    /usr/local/bin/ruby extconf.rb creating Makefile
  </code></pre>
    
    <p>make Makefile:158: <em>*</em> target pattern contains no `%'.  Stop.</p>
    
    <p>Gem files will remain installed in
    /srv/www/socialu.com/https:/github.com/willfults/rails3-jquery-autocomplete.git/ruby/1.9.1/gems/json-1.7.5
    for inspection. Results logged to
    /srv/www/socialu.com/https:/github.com/willfults/rails3-jquery-autocomplete.git/ruby/1.9.1/gems/json-1.7.5/ext/json/ext/generator/gem_make.out
    An error occured while installing json (1.7.5), and Bundler cannot
    continue. Make sure that <code>gem install json -v '1.7.5'</code> succeeds before
    bundling.</p>
  </blockquote>
  
  <p>I tried doing the following <code>sudo aptitude install ruby1.9.1-dev</code> but that didn't work.  </p>