title: gulp-compass asking for Ruby and Compass in PATH when they are already there
body: <p>I'm trying to get <a href="https://www.npmjs.com/package/gulp-compass" rel="nofollow">gulp-compass</a> to work on my Debian linux but am getting an error message stating that Ruby and Compass must be in the path.  I am a bit of a beginner when it comes to Gulp so is probably me being stupid.</p>
  
  <p>The following is the exact error message I get when running the task I create in my Gulpfile:</p>
  
  <pre><code>events.js:85
        throw er; // Unhandled 'error' event
              ^
  Error: You need to have Ruby and Compass installed and in your system PATH for this task to work.
  
  Process finished with exit code 1
  </code></pre>
  
  <p>I've looked through other similar questions that suggest doing a <code>gem install compass</code> and a <code>gem install sass</code> but neither seem to work for me.</p>
  
  <p>My Gulpfile is as follows:</p>
  
  <pre><code>var gulp = require('gulp'),
  compass = require('gulp-compass');
  
  gulp.task('stylesheets', function(){
      return gulp.src('**/*.scss')
          .pipe(compass({
              config_file: './config.rb',
              css: 'css',
              sass: 'sass'
          }))
          .pipe(gulp.dest('css'));
  });
  </code></pre>
  
  <p>I can run<code>ruby -v</code> and <code>compass -v</code> I can see that these are correctly in my path and doing an <code>echo $PATH</code> shows that ruby is definitely there.</p>
  
  <p>I am wondering if it is a problem to do with me installing ruby with RVM or the fact that I am using Bundler to install the gems in my project.  My Gemfile is as follows:</p>
  
  <pre><code>source 'https://rubygems.org'
  gem 'susy'
  gem 'compass'
  gem 'breakpoint'
  </code></pre>
  
  <p>I have installed the gems with <code>bundle install</code> and have also tried the <code>bundle_exec: true</code> option in gulp-compass (though truth be told I don't really know what this is for not being a Bundler expert). I have tried re-installing Ruby.</p>
  
  <p>Has anyone any idea as to why I am getting the above error message?  I've never had errors like this when doing similar with Grunt.</p>