Added string replace utility to stout.

From: Vinod Kone <vinodkone@gmail.com>
Review: https://reviews.apache.org/r/8043

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1451039 13f79535-47bb-0310-9956-ffa450edef68
Added 'MesosTest' test fixture to properly setup
and teardown slave working directory.

From: Vinod Kone <vinodkone@gmail.com>
Review: https://reviews.apache.org/r/8055

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1451040 13f79535-47bb-0310-9956-ffa450edef68
Added helpers to extract cpus, mem, disk and ports
from resources.

From: Vinod Kone <vinodkone@gmail.com>
Review: https://reviews.apache.org/r/8145

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1451041 13f79535-47bb-0310-9956-ffa450edef68