title: Transform Date Dataframe
body: <p>I have a dataframe that looks something like this:</p>
  <pre><code>County    2020-01-22  2020-01-23  2020-01-24
  Autauga   0           1           0
  Baldwin   0           2           4
  Barbour   0           3           1
  </code></pre>
  <p>However, I would like to reformat it so that I get counts per day by county. Something like this:</p>
  <pre><code>County   year  month  day  value 
  Autauga  2020  01     22   0
  Baldwin  2020  01     22   0
  Barbour  2020  01     22   0
  Autauga  2020  01     23   1
  Baldwin  2020  01     23   2
  Barbour  2020  01     23   3
  Autauga  2020  01     24   0
  Baldwin  2020  01     24   4
  Barbour  2020  01     24   1
  </code></pre>