title: How to obtain first day of next month in ruby?
body: <p>I have a date of operation. I want create promissory notes which have got:</p>
  
  <pre><code>day=1
  month= the next month of operation_date
  year= automatic
  </code></pre>
  
  <p>Example :</p>
  
  <pre><code>operation_date = 15/11/2010 
  promissory_note1_date = 1/12/2010
  promissory_note2_date = 1/01/2011
  promissory_note3_date = 1/02/2011
  promissory_note4_date = 1/02/2011
  </code></pre>
  
  <p>if exist four promissory notes</p>
  
  <p>How could I make it?</p>
  
  <p>PD: Excuse me my syntax</p>