Removed /vars endpoints from the Master and Slave.

Review: https://reviews.apache.org/r/13048
Added /health endpoints to the Master and Slave.

Review: https://reviews.apache.org/r/13049
Added help for the /master/redirect endpoint.

Review: https://reviews.apache.org/r/13076
Updated the launcher to redirect stderr/stdout during forked setup.

Review: https://reviews.apache.org/r/13177/
Update email addresses for the dev list.

Change references of 'mesos-dev@incubator.apache.org' to
'dev@mesos.apache.org'. Also, changing
'mesos-dev-subscribe@incubator.apache.org' to
'dev-subscribe@mesos.apache.org'.

From: Matthew Silvey <matthew@dancewithdevils.com>
Review: https://reviews.apache.org/r/12980
Revert flag environment variable semantics.

Now environment variables will be "tried" to be applied as flags but
if no flag is known given an environment variable then the loader will
not fail.

Review: https://reviews.apache.org/r/13173
Added MESOS_NATIVE_LIBRARY to launcher.

Review: https://reviews.apache.org/r/13174
Set MESOS_NATIVE_LIBRARY in the testing environment.

We want to force our tests (including the Java ones) to use the most
recent version of our library, so we set MESOS_NATIVE_LIBRARY.

Review: https://reviews.apache.org/r/13175
Cleaned up the pre-installed "wrappers".

Review: https://reviews.apache.org/r/13176
Add '-fno-strict-aliasing' for gcc 4.4.*.

Review: https://reviews.apache.org/r/13182
Updated configure.ac to properly check for Python.h.

Review: https://reviews.apache.org/r/13194
Don't make the mesos-*-flags.sh executable.

Review: https://reviews.apache.org/r/13205
Use 'exec' to launch mesos-slave from wrapper.

Review: https://reviews.apache.org/r/13206
Added checkpoint parameter to JobTracker.

Now it's possible to set checkpoint=true for the Hadoop framework by
specifying mapred.mesos.checkpoint=true in the Hadoop config.

Review: https://reviews.apache.org/r/13091