title: Generate random float numbers in FactoryGirl
body: <p>I need to generate random latitude and longitude values in my factories for testing, but using <code>Random</code> class gives me duplicate values and make my tests fail, how can I generate random float values in <code>FactoryGirl</code>?</p>
  
  <p><strong>EDIT</strong>: the relevant piece of code</p>
  
  <pre><code>factory :location do
    lat rand(-90.0..90.0)
    lng rand(-180.0..180.0)
  end
  </code></pre>