More info in returned SampleSet

[kevinchern]

Problem

1. SampleSet returned by neal has no timing info analogous to DWaveSampler().sample(...).info['timing']
2. Other useful bits of info like
   num_sweeps_per_beta = max(1, num_sweeps // 1000.0), num_betas = int(math.ceil(num_sweeps / num_sweeps_per_beta)) are missing

Context

1. Useful for accurate and consistent timings, and
2. For noting the discrepancy between actual number of sweeps vs input number of sweeps (and thus schedule)