title: filter/select rows of pandas dataframe by timestamp column
body: <p>I am new to pandas. I have dataframe with two columns dt (date-time stamp) and value.</p>
  
  <p>Given two start and end data-time stamps: is there a easy way to create a new dataframe from original one that contains rows between the two date-time stamp?</p>
  
  <pre><code>                dt    value
  84    7/23/2014 7:00  0.300
  85    7/23/2014 7:05  0.300
  86    7/23/2014 7:10  0.312
  87    7/23/2014 7:15  0.300
  88    7/23/2014 7:20  0.300
  89    7/23/2014 7:25  0.300
  90    7/23/2014 7:30  0.300
  91    7/23/2014 7:35  0.300
  92    7/23/2014 7:40  0.300
  93    7/23/2014 7:45  0.216
  94    7/23/2014 7:50  0.204
  95    7/23/2014 7:55  0.228
  96    7/23/2014 8:00  0.228
  97    7/23/2014 8:05  0.228
  98    7/23/2014 8:10  0.228
  99    7/23/2014 8:15  0.240
  100   7/23/2014 8:20  0.228
  101   7/23/2014 8:25  0.216
  102   7/23/2014 8:30  0.228
  103   7/23/2014 8:35  0.324
  104   7/23/2014 8:40  0.336
  105   7/23/2014 8:45  0.324
  106   7/23/2014 8:50  0.324
  107   7/23/2014 8:55  0.324
  108   7/23/2014 9:00  0.252
  109   7/23/2014 9:05  0.252
  110   7/23/2014 9:10  0.240
  111   7/23/2014 9:15  0.240
  112   7/23/2014 9:20  0.252
  113   7/23/2014 9:25  0.240
  ..               ...    ...
  198  7/23/2014 16:30  0.132
  199  7/23/2014 16:35  0.120
  200  7/23/2014 16:40  0.180
  201  7/23/2014 16:45  0.216
  202  7/23/2014 16:50  0.204
  203  7/23/2014 16:55  0.192
  </code></pre>