title: whenever gem: hourly tasks with minute set
body: <p>I have a bunch of cronjobs managed by whenever.  Everything works fine, but I have a few hourly cronjobs that are all triggered at the same time, so I'd like to stagger them.  Worst case scenario I'm able to update the crontab manually, but I'd really rather take of this in schedule.rb.</p>
  
  <p>TL;DR - I would like to do something like:</p>
  
  <pre><code>every 1.hour, at: ":00" do #task 1
  every 1.hour, at: ":10" do #task 2
  every 1.hour, at: ":20" do #task 3
  </code></pre>
  
  <p>Thanks!</p>