Fixed the Balloon Framework Test.

Stop exporting variables that begin with MESOS_ into the mesos
environment. The mesos-master and mesos-slave binaries will not start
if there are unrecognized variables that begin with MESOS_ in the
environment.

Set the LD_LIBRARY_PATH so that the balloon binaries built with
libtool will be able to find all of their pieces and execute properly
without needing to be installed.

Cleanup the cleanup code so we don't unmount a cgroup hierarchy unless
we have fully cleaned it up. This is necessary to prevent a problem
where the hierarchy can never be mounted again.

Update the command line options to mesos-master to pass the hierarchy
and the mesos root directory in that hierarchy.

Clearly report when the balloon hierarchy returns with an unexpected
return code in order to indicate whether the test failed because of a
problem in the baloon framework or within mesos.

From: Eric Biederman <ebiederm@xmission.com>
Review: https://reviews.apache.org/r/13034
Added a test for slave recovery when a scheduler failover happens.

From: Jie Yu <yujie.jay@gmail.com>
Review: https://reviews.apache.org/r/13677
Added slave recovery network partition test.

From: Jie Yu <yujie.jay@gmail.com>
Review: https://reviews.apache.org/r/13723
Fixed slave recovery tests to use 'strict' option by default.

Review: https://reviews.apache.org/r/13676
Fixed slave to not log a warning when it generates TASK_LOST update.

Review: https://reviews.apache.org/r/13715
Fixed SlaveRecovery.Partitioned slave test.

Review: https://reviews.apache.org/r/13729
Simplified os::hostname() in libstout.

Review: https://reviews.apache.org/r/11108
Shuffle offers before sending to frameworks.

This helps ensure fair allocation of resources.

Review: https://reviews.apache.org/r/11121
Added --enable-debug configure flag.

Review: https://reviews.apache.org/r/11605
Slave ping timeout may be increased by flags.

Review: https://reviews.apache.org/r/12885
Turned down noise from ZooKeeper.

Review: https://reviews.apache.org/r/11127
Fixed broken build on GCC 4.8 due to -Wall.

With GCC 4.8, Boost fails to build from '-Wunused-local-typedefs', which
is implied by '-Wall'.

Review: https://reviews.apache.org/r/11974/
Use hostname instead of IP for redirection.

In the Web UI, the redirection does not work for hosts where the local
interface address is not publicly accessible.  For example, with EC2 the
redirection will not work.

This change writes the Master's hostname into ZooKeeper, thereby
allowing the redirection to work with private IP addresses.

Review: https://reviews.apache.org/r/11975/
On recovery fail, do rm -rf /tmp/mesos/meta.
Use libstout cache for slave completedFrameworks.

The list of retired (completed) frameworks is now a stout cache rather
than a boost circular buffer.  There are now key iterator accessors for
the cache class, and a removal member.

Review: https://reviews.apache.org/r/13599
Added a slave load hint for scheduler sorting.

With this change, the offers will include a slave load hint based on the
5 minute load average for that slave (returned from getloadavg()).
Frameworks can use this hint to select among otherwise similar offers,
as an optimization.

Review: https://reviews.apache.org/r/13675