Inconsistent shape of metrics files

[allisonmcampbell]

(At least) two metrics files have different shapes accounting for the time stamps / hours

The pypower metrics files -- {case}_mdict.json, bus{case}metrics.json, gen{case}_metrics.json -- all have 577 time stamps. The GLD metrics files -- {case}_glmdict.json, substation{case}metrics.json, house{case}_metrics.json, billingmeter{case}metrics.json, inverter{case}metrics.json, capacitor{case}metrics.json, regulator{case}_metrics.json -- all have 576 time stamps.

The inconsistency comes from the GLD metrics files not having an entry for time = '0' (zero), whereas this exists (with content) for the pypower metrics files.

[trevorhardy]

We're going to address this in our API re-work where we hope to have a more consistent data management strategy.