Updates debian rules to use different thermos_observer.
Updates debian rules to use different thermos_observer.

The old thermos_observer is missing the --mesos-root flag thats needed
to tell the thermos_observer where it can find the mesos root directory.
It currently defaults to /var/lib/mesos in the old observer entry point.

Testing Done:
1. Built aurora with dpkg-buildpackage -us -uc -d
2. Installed executor deb: dpkg --install aurora-executor_0.9.0-SNAPSHOT_amd64.deb
3. thermos_observer --long-help
Options:
  -h, --help, --short-help
                        show this help message and exit.
  --long-help           show options from all registered modules, not just the
                        __main__ module.
  --root=ROOT           The thermos checkpoint root directory to search for
                        Thermos tasks [default: /var/run/thermos]
  --mesos-root=MESOS_ROOT
                        The mesos root directory to search for Thermos
                        executor sandboxes [default: /var/lib/mesos]
  --port=PORT           The port on which the observer should listen.
                        [default: 1338]
  --polling_interval_secs=POLLING_INTERVAL_SECS
                        The number of seconds between observer refresh
                        attempts. [default: 5]

I am in the process of building and deploying this change to production and can report
back when that is complete.

Bugs closed: AURORA-1403

Reviewed at https://reviews.apache.org/r/36644/

medallia/aurora,wfarner/aurora,protochron/aurora,apache/aurora,medallia/aurora,thinker0/aurora,rosmo/aurora,shahankhatch/aurora,wfarner/aurora,mschenck/aurora,medallia/aurora,protochron/aurora,rdelval/aurora,rosmo/aurora,protochron/aurora,apache/aurora,thinker0/aurora,rosmo/aurora,protochron/aurora,crashlytics/aurora,rdelval/aurora,shahankhatch/aurora,thinker0/aurora,mschenck/aurora,wfarner/aurora,thinker0/aurora,rdelval/aurora,rosmo/aurora,crashlytics/aurora,shahankhatch/aurora,crashlytics/aurora,kidaa/aurora,mschenck/aurora,shahankhatch/aurora,apache/aurora,crashlytics/aurora,medallia/aurora,medallia/aurora,kidaa/aurora,mschenck/aurora,apache/aurora,mschenck/aurora,rosmo/aurora,rosmo/aurora,thinker0/aurora,kidaa/aurora,protochron/aurora,medallia/aurora,wfarner/aurora,thinker0/aurora,wfarner/aurora,apache/aurora,crashlytics/aurora,crashlytics/aurora,apache/aurora,rdelval/aurora,rdelval/aurora,shahankhatch/aurora,shahankhatch/aurora,kidaa/aurora,wfarner/aurora,kidaa/aurora,mschenck/aurora,protochron/aurora,rdelval/aurora,kidaa/aurora