title: Error installing json gem: The 'json' native gem requires installed build tools
body: <p>When i'm trying to install this gem it claims that i need to have a devkit installed although i am sure i do have it. It also suggests that i need to update my systems variables in PATH which i have directly linked to the devkit file in ruby. I have seen other questions on Stack Overflow and they didn't work with my issue.
  here is the full error message:</p>
  
  <pre><code>C:\Users\Mahamoud&gt;gem install json
  ERROR:  Error installing json:
          The 'json' native gem requires installed build tools.
  
  Please update your PATH to include build tools or download the DevKit
  from 'http://rubyinstaller.org/downloads' and follow the instructions
  at 'http://github.com/oneclick/rubyinstaller/wiki/Development-Kit'
  </code></pre>
  
  <p>I've tried uninstalling and re installing ruby and still no result.
  i have my devkit located in the C:\Ruby193\bin</p>