title: Julia DataFrames, Insert new row at specific index
body: <p>Is there a way to add a row to an existing dataframe at a specific index?</p>
  
  <p>E.g. you have a dataframe with 3 rows and 1 columns</p>
  
  <pre><code>df = DataFrame(x = [2,3,4])
  
  X
  2
  3
  4
  </code></pre>
  
  <p>any way to do the following:</p>
  
  <pre><code>insert!(df, 1, [1])
  </code></pre>
  
  <p>in order to get</p>
  
  <pre><code>X
  1
  2
  3
  4
  </code></pre>
  
  <p>I know that i could probably concat two dataframes df = [df1; df2] but i was hoping to avoid garbaging a large DF whenever i want to insert a row.</p>