Hid links to dead slaves to prevent dead links.

If a slave is gone, the framework page will print "Slave gone" in place
of the links to the slave's UI. The links would previously fail in
redirection and return the user to the Mesos root page, which is
unpleasant.

Fixes: https://issues.apache.org/jira/browse/MESOS-650

Review: http://reviews.apache.org/r/14074
Removes 90 day plan from documentation, which is no longer relevant.
Updates formatting of heads on Mesos presentations documentation.
Cleaned up some log and CHECK messages.

Review: https://reviews.apache.org/r/14135
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/
Updates Powered by Mesos list to include MediaCrossing and Xogito.
Updates Mesos Roadmap to point to JIRA.
Removes out of date Hadoop on Mesos documentation from 2011.
Removes previously revised date, and updates information regarding downloading the latest release.
Fixed build breakage from 37e946683f1bb6a.

In 37e946683f1bb6a I fixed a build failure from a warning, which are
treated as errors.

Newer versions of GCC have a feature (documented here:
http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html) where unknown
warning flags are ignored.

In older version of GCC (such as 4.1 or 4.2), it appears that these flags
aren't ignored, resulting in an error.

Review: https://reviews.apache.org/r/14164
Check for automake 1.14 in bootstrap.

Review: https://reviews.apache.org/r/14183
Updated CHANGELOG and docs for 0.14.0.
Moved Jenkins out of the repo to
https://github.com/jenkinsci/mesos-plugin.
Removed references of jenkins from Makefile.am and configure.ac.
Updates Powered by Mesos list to include sharethrough.