title: Sinew (ruby web scraper) example does not work on my machine
body: <p>I'm trying to run the sample from the sinew source code, but it's not working on my machine.  Here is the sample (taken directly from their github):</p>
  
  <pre><code>get "http://www.amazon.com/gp/bestsellers/books/ref=sv_b_3"
  noko.css(".zg_itemRow").each do |item|
    row = { }
    row[:url] = item.css(".zg_title a").first[:href]
    row[:title] = item.css(".zg_title")
    row[:img] = item.css(".zg_itemImage_normal img").first[:src]
    csv_emit(row)
  end
  </code></pre>
  
  <p>I'm using ubuntu 12.04 with ruby 1.9.3 and rvm.  Here is what I typed in, followed by the error.</p>
  
  <pre><code>jefferton@ubuntu:~/IdeaProjects/sinew_scrape$ sinew sell_list.sinew
  curl http://www.amazon.com/gp/bestsellers/books/ref=sv_b_3
  /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/lib/sinew/text_util.rb:48:in `popen': No such file or directory - tidy -asxml  -bare  -quiet  -utf8  -wrap 0 --doctype omit --hide-comments yes --force-output yes -f /dev/null (Errno::ENOENT)
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/lib/sinew/text_util.rb:48:in `html_tidy'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/lib/sinew/main.rb:33:in `html'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/lib/sinew/main.rb:59:in `noko'
  from sell_list.sinew:9:in `_run'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/lib/sinew/main.rb:121:in `instance_eval'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/lib/sinew/main.rb:121:in `_run'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/lib/sinew/main.rb:16:in `initialize'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/bin/sinew:19:in `new'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/bin/sinew:19:in `block in &lt;top (required)&gt;'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/bin/sinew:18:in `each'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/gems/sinew-1.0.2/bin/sinew:18:in `&lt;top (required)&gt;'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/bin/sinew:19:in `load'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/bin/sinew:19:in `&lt;main&gt;'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/bin/ruby_noexec_wrapper:14:in `eval'
  from /home/jefferton/.rvm/gems/ruby-1.9.3-head/bin/ruby_noexec_wrapper:14:in `&lt;main&gt;'
  </code></pre>
  
  <p>I wish I knew a more specific thing to ask, but I'm not sure what to do here.</p>
  
  <p>Thanks.</p>