Add : ability to restrain to some benchmarks at BenchCase construction
Add : ability to restrain to some benchmarks at BenchCase construction

BenchCase __init__ method now accepts a `methods` arguments which
the execution can be restrained to.
For example, you've got a BenchCase class which few benchmarks: ['bench_this',
'bench_it', 'bench_that'], you can construct it like BenchCase('bench_this') or
BenchCase(['bench_that', 'bench_it']) and it's benchmarks will be restrained
to these methods when you run it.

oleiade/Hurdles