Cleanup of report rendering handler

Thanks to some input from the Jenkins mailing list, I discovered
a much, much cleaner way to implement the request routing
for serving up the Gatling reports in the Jenkins UI.

This commit provides no functional changes, but the code is much
cleaner and more maintainable.
Merge pull request #4 from cprice-puppet/feature/master/support-multiple-sims-in-single-build

Cleanup of report rendering handler