The Mesos slave has many different flags and different user have
different requirement for different parameters, add isolation,
work_dir, image_providers parameters for slave in mesos bay to
give end user more choice. for example Set the parameters to
support Container Images in Mesos Containerizer
Note: support Container Images in Mesos Containerizer needs mesos
version >= 0.28
Partially-Implements:blueprint mesos-slave-flags
Change-Id: Ib4fd7076704a3266f0cf2addf08896729ec6062f