title: Getting the first and last day of a month in ruby from partial string
body: <p>I have a table with a column for <code>year</code>, which is an <code>integer</code>, and a column for <code>month</code>, which again is an <code>integer</code>. I need (in ruby) to be able to end up with a <code>start_date</code> and an <code>end_date</code> for each row. </p>
  
  <p>So from the first row, where the year is 2016 and the month is 1, I need to get start_date = 01/01/2016 and end date = 31/01/2016. i know I can get them in ruby with beginning_of_month and end_of_month, but I need to get to a date first?</p>
  
  <p>I'm getting lost in Date.parse and Date.strptime, and could really do with someone explaining it. Presumably I cannot get a date to begin with because I don't actually have a day to work with !</p>
  
  <p>help :)</p>