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