title: guard gem run all triggers on start
body: <p>Hi this is driving me crazy. I couldn't find a solution after a long time.</p>
  
  <p>How do I trigger a "run_all" for all guards in the Guardfile.</p>
  
  <p>When i run "guard" in the shell, I want it to sort off pretend like all files have changed and trigger all guards.</p>
  
  <p>What's a clean way to do this from the Guardfile.</p>