Added instructions for getting started with CentOS.

Review: https://reviews.apache.org/r/25272
Added Resources support to return the port range for the given number of ports.

Review: https://reviews.apache.org/r/24810
Updated the container failed to launch error message in the slave.

Review: https://reviews.apache.org/r/25273
Count pending tasks as staging in the slave.

Review: https://reviews.apache.org/r/25302
Fixed a bug in the staging tasks metric.

Review: https://reviews.apache.org/r/25303
Removed an unnecessarily introduced Option.

Review: https://reviews.apache.org/r/25304
Flattened the executor resoures when launching executors.

Review: https://reviews.apache.org/r/25306
Fixed the memory limitation construction.
Improved the error message when destroying a container.

Review: https://reviews.apache.org/r/25344
Minor update to include package config file

Minor update to include package config file

Review: https://reviews.apache.org/r/25355
Added optional --offer_timeout to rescind unused offers.

The ability to set an offer timeout helps prevent unfair resource
allocations in the face of frameworks that hoard offers, or that
accidentally drop offers.

When optimistic offers are added, hoarding will not affect the
fairness for other frameworks.

Review: https://reviews.apache.org/r/22066
Fix protobuf detection on systems with Python 3 as default

MESOS-1774

Review: https://reviews.apache.org/r/25439
Added kill() to freezerTimedOut() in cgroups.cpp.
This is a short-term fix for MESOS-1758.

Review: https://reviews.apache.org/r/25457
Fixed python egg proto imports.

Fixes defective import introduced by the flat folder hierachy of the mesos.interface Python egg generation.

Review: https://reviews.apache.org/r/25334
Updated the Mesos C++ Style Guide.

Review: https://reviews.apache.org/r/25274
Update deploy_dir from localstate to sysconf

Updates the mesos-env files to install to /etc/mesos vs. /var/lib/deploy/mesos.

Review: https://reviews.apache.org/r/25447
Fixed line comments end punctuation in Mesos source.

Review: https://reviews.apache.org/r/23707
Fixed line comments end punctuation in stout.

Review: https://reviews.apache.org/r/23708
Fixed line comments end punctuation in libprocess.

Review: https://reviews.apache.org/r/23709
Adds Qubit to PoweredByMesos list.