title: Insert rows into tensor in Tensorflow
body: <p>Simply, I am looking for a way to insert zero value rows at specific locations into one tensor. That is, given a tensor <code>A</code> for example, and list of <code>rows=[1, 3]</code>, I would like to get the following tensor <code>B</code>:</p>
  
  <pre><code>    | ? ? ? |       | ? 0 ? 0 ? |
  A = | ? ? ? |   B = | ? 0 ? 0 ? |
      | ? ? ? |       | ? 0 ? 0 ? |
  </code></pre>