Endpoint size histogram, supports for both default and user-supplied endpoint sizes

Hi Riccardo,

  I am sending you my code regarding the little tweaks I did to the performance test.  The code supports both the default values and any user-supplied sizes for the endpoints.  It is very easy to switch back and forth between a bounded and an unbounded queue (in case we want to test that again).  I also added an histogram of the observed sizes, so we have a better picture of the memory usage during the test.

  I added a comment in the code (feel free to remove it, and remove the associated test if you think it is relevant anymore) explaining why the SEDA LONG test takes so long.  I'll bring it to the attention of the Camel developers.  In brief, there is a call to a log debug that even though debug is not turned on, it still has to evaluate DefaultEndpoint.toString()...