title: Create paired boxplots, from 2 distinct dataframes
body: <p>I would like to create a graphic with box plot in R. I got the following data frames:</p>
  
  <pre><code>&gt; drools_responseTimes_numberOfClients_REST
        X1   X5  X10  X20   X50
  1    816  183  699  154   297
  2    366  280 1283  345   291
  3    103  946 1609  409   377
  4    431 1086 1974  482   479
  5     90 1379 2083  567   557
  6    290  511 2184  910   925
  7    134  770 2283  980  1277
  8    480 1547 2416 1069  1752
  9    275 1727 2520 1141  1846
  10    67  679 2616 1188  1935
  
  &gt; javascript_responseTimes_numberOfClients_REST
         X1   X5  X10   X20   X50
  1     334  497  610   439   417
  2     445  894  859   826   588
  3     306 1143 1123  1407   791
  4     301 1442 1445  1806  1005
  5     257 1754 1857  2209  1235
  6     181  507 2078  2493  1441
  7     436 1186 2419  2885  1677
  8     353 2280 2708  3101  1909
  9     350 2984 2997  3358  2106
  10    296  544 3185  3817  2353
  </code></pre>
  
  <p>I want to create paired box plot for each column distinguishing the type by the color as shown here: <a href="https://stackoverflow.com/a/17922219/3503168">https://stackoverflow.com/a/17922219/3503168</a></p>