title: using dotenv variables inside capistrano 3 custom task
body: <p>I'm trying to create capistrano task that will show a variable set by dotenv from .env file</p>
  
  <p>the task:</p>
  
  <pre><code>namespace :test do
    task :env do
      on roles(:app) do
        info ENV['TEST_ENV'].inspect
      end
    end
  end
  </code></pre>
  
  <p>.env file:</p>
  
  <pre><code>TEST_ENV='confusing'
  </code></pre>
  
  <p>running the task:</p>
  
  <pre><code>$ cap staging test:env
  DEBUG [37c8a9e6] Running /usr/bin/env [ ! -d ~/.rbenv/versions/2.0.0-p353 ] on x.x.x.x
  DEBUG [37c8a9e6] Command: [ ! -d ~/.rbenv/versions/2.0.0-p353 ]
  DEBUG [37c8a9e6] Finished in 14.776 seconds with exit status 1 (failed).
   INFO nil
  </code></pre>
  
  <p>this is under a working capified rails 4 app (I can run cap staging deploy just fine)</p>
  
  <p>anyone can tell me what am I missing please?</p>
  
  <p>edit:</p>
  
  <p>as it might not be clear enough, what I actually need is to access .env in my local machine, the actual case:</p>
  
  <blockquote>
    <p>I store a secret api key inside .env and it will be used to notify external api service after deploy, the api key itself isn't supposed to be stored anywhere else and is app exclusive (each app have its own key) so it's not a good idea to store it permanently in local env</p>
  </blockquote>