Add support for nyc --all flag

[tonywoode]

nyc has the following flag
however mochista has its own --all flag, which has unrelated functionality
Are you planning to support the nyc --all flag?

[laggingreflex]

I might, but it's not a priority for me personally at the moment so I'll have to postpone it to the future. PR welcome though.

Right now the way it works is that it registers a require hook (hooks into all require calls) and thus it can only know about the files that are actually required. (related code: https://github.com/laggingreflex/mochista/blob/master/src/istanbul/instrument/index.js#L19)

Such a functionality will need to re-write whatever nyc does to include all files that aren't required by the testing (mocha) code.

[garex]

Currently nyc has --all flag in package.json, but as I understand, mochista not used any nyc settings.

Sad, but this is show stopper for me.

[laggingreflex]

Added. a2db9f2 7f8900d Released 0.12.2. Please check it out and let me know.

[garex]

@laggingreflex tnx!