Resolve "Benchmark definition standard"

Addresses issue #8 (closed) (define a standard output for our tests/benchmarks, where a benchmark is a specific collection of tests). I put the boilerplate benchmark code under util/benchmark.hh for now (should ultimately be factored into an external library). I added some benchmark code to the dvmp/vm_mass benchmark to start.

dvmp/analysis/benchmark.hh

+../../util/benchmark.hh
\ No newline at end of file