Renamed Cfs test to properly disable in non-root non-linux environment.

Review: https://reviews.apache.org/r/18634
Fixed Cpu isolator to use integral values for cfs quota.

Review: https://reviews.apache.org/r/18639
Refactored cpu control writes.

Review: https://reviews.apache.org/r/18642
Added completed frameworks/tasks to slave re-registration.

Fixes MESOS-767.

Review: https://reviews.apache.org/r/16724