Updated statistic calculation in heartbeat and broke it out to separate function.
Added resource grouping method.
Added taskSamples for preference marking.
Added stub for CPU or disk-based scheduling while defaulting to standard scheduler.
Updated groups to be views of full offers list instead of copies.
Threaded NodeStats through to be available on executor addition.
Separated scheduling logic.
Implemented specialized schedulers.
Converted MHz to milliseconds in stats.
Added support for presented paper model.
Merge pull request #2 from DeathByTape/Scheduler

First working scheduler implementation. Improvements likely to come.