Extension to Bong for providing visual output
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After running bong a number of times, provide a visual output with time on the x axis and req/second on the y axis
Intended to show the change in performance throughout the development of a project
 
Assumptions
* Each run will be named "benchmark-1216122887" where the second part can be converted to a Time class using Time.at(..)
* Runs will be displayed at equal intervals along the x axis regardless of if the time between them is uniform
* Several URLs may be incldued. rps for each one will be of a similar order of magnitude, so it makes sense to graph them together
* Not all URLs will have data in all runs. However once a url is added it will be in ALL subsequent runs