Scalameter for java code

Please note that I've worked on version forked from http://axel22.github.com/scalameter/.
Also, I have a NullPointerException at the end of regression tests, even with scala code coming from HTMLReporter.scala at line 167. I have not been able to determine if it comes from my code, or my computer...
You should introduce a new intermediate `trait` and call it `BasePerformanceTest`, instead of using `DSL` directly here.