Generalize the benchmark 'class' and 'method'

```
If a benchmark 'class' and benchmark 'method' did not strictly have to be a
Java class and Java method, it would enable benchmarks written in other
languages. (We have an interested user at Google.)

We'd need something to be responsible for finding the benchmark methods and
setting up the benchmark "instance", so that something could be swapped out
independently of the selection of Instrument.

This is undoubtedly complex.
```

Original issue reported on code.google.com by `kevinb@google.com` on 10 Oct 2011 at 7:44