title: Passing format as parameter to rake spec
body: <p>My question is similar to <a href="https://stackoverflow.com/questions/2890521/how-to-pass-f-specdoc-option-through-rake-task">this </a>, where they want to override <code>rake spec</code>'s output format.  The resolution to that question is to use the .rspec config file, which is limiting.  I would like this to be a command line argument because  I want this to vary on different machines.</p>
  
  <p>The rspec executable has the <code>-f</code> option be defining format. <code>rake spec</code> has <code>-f</code> defining a rakefile. <code>rake spec --format</code> is invalid.  Is this an oversight in <code>rake spec</code>?  "Format" really isn't an option?</p>