Minor fix to SlaveReregistersFirst and FrameworkReregistersFirst
allocator tests.
Updated Getting Started page for 0.19.0.
Fixed some Javadoc errors.
Improved gate.hpp documentation.

Review: https://reviews.apache.org/r/18988
Created an example LoadGeneratorScheduler to test Master's framework rate limiting feature.

Review: https://reviews.apache.org/r/23250
PortMapping: allow containers to recover even when they were not
managed by Network Isolator previously.

This eases deployment where a slave could be upgraded to use Network
Isolator without removing all the existing tasks.

- Added a new test.
- Moved all portmapping tests to a new file.

Review: https://reviews.apache.org/r/23214
Minor fix to mesos_tests_SOURCES in Makefile.am
Adds collectd plugin to Mesos tools documentation.
HTTP Authenticated '/shutdown' endpoint.

Review: https://reviews.apache.org/r/22832
Fixed the recovery timeout in the tests.
Fixed health check command subprocess handling.

Currently it doesn't check all subprocess future states, and also
creates a pipe to stdin which can cause some scripts to expect stdin
input and blocks.

Review: https://reviews.apache.org/r/23416
Add Sailthru to the "Powered by Mesos" page.

This closes: #21
Review: https://github.com/apache/mesos/pull/21
Added CHANGELOG for 0.19.1.
Updated the upgrades document for 0.18.2 and 0.19.1.
Added logging to vote.sh to help debug a confusing exit.
Unbundled picojson

Enable mesos to build against the system installed version of picojson.

Review: https://reviews.apache.org/r/23091
Unbundled libev

Enable mesos to build against the system installed version of libev.

Review: https://reviews.apache.org/r/23414
Send an unregister message when the slave is shutting itself down.

Review: https://reviews.apache.org/r/22367
Added metrics for port mapping network isolator.

Review: https://reviews.apache.org/r/23492
Fix executor passing STDIN pipe to health check.

Previous fix for STDIN only fixes the health check command not passing
in STDIN pipe by reading file STDIN. However the health check command
is still getting STDIN piped as the command executor is creating a
PIPE to STDIN when launching health check. To really fix this we need
to also fix not passing anything to STDIN when launching health check.

Review: https://reviews.apache.org/r/23518