Add workplace verification before render content.
    
    - Previously, render module didn't verify whether the working
      directory was a supported working directory or not. As consequence,
      variable expansion inside configuration files at render time might
      be expanded to a value different from that expected. This update
      changes the render module to verify the workplace before render any
      content.
    
      The main problem solved here is the correct expansion of
      TCAR_WORKDIR variable value. If the working directory isn't
      verified, and this value isn't retrieved from the configuration file
      inside it, TCAR_WORKDIR is expanded to its default value which might
      be not the place where your working directory is really stored in.
      As consequence, automation script will try to take content from a
      place that might not exist, making the automation scripts to fail at
      some point.