PortMappingIsolator: Swap TX/RX in statistic collection in usage

statistics collected on the host end of veth pair have reversed RX/TX of those in the container.

Review: https://reviews.apache.org/r/27154
Added a check in routing library due to a bug in libnl.

Review: https://reviews.apache.org/r/27105
Added documentation for egress rate limit control.

Review: https://reviews.apache.org/r/26423
Reordered functions in type_utils and added an equal comparator for
Volume.

Review: https://reviews.apache.org/r/27150
Adds Wizcorp to PoweredByMesos page.
Added Java replicated log implementation of State.

Review: https://reviews.apache.org/r/24341
Added functionality to create SVN based diffs of arbitrary strings.

Review: https://reviews.apache.org/r/24535
Added DIFF to the replicated log state storage implementation.

Review: https://reviews.apache.org/r/24536
Ensured post-reviews.py added newline between subject and body.
Updated svn::diff/patch to use newer versions of functions.
Added --with-apr and --with-svn to libprocess configure.
Added --with-apr and --with-svn to Mesos configure.
Fixed line wrap in state/log.cpp.
Adds Localsensor to PoweredByMesos documentation.
Pass executor directory to Isolator::prepare().

Review: https://reviews.apache.org/r/24177
Serialize isolator prepare and cleanup (reversed).

Review: https://reviews.apache.org/r/25861
Remove /proc and /sys remounts from port_mapping isolator.

Review: https://reviews.apache.org/r/26274
Introduce a shared filesytem isolator.

Isolator supports creating private copies of system directories, e.g.,
/tmp, for each container while sharing the host's filesystem.

Review: https://reviews.apache.org/r/25549
Add Artirix to PoweredByMesos list.
Added --isolation flag for tests.

This is useful to test custom isolation modules with the test suite.
The user can specify the available modules with --modules and then he
can specify the isolator module with the --isolation flag.
With these flags, the test suite will run all tests with the specified
isolator modules.

Review: https://reviews.apache.org/r/26797