Save juju status on Talisman

[tvansteenburgh]

I haven't been able to repro #122, so I'm adding a way to debug when it happens again. Now we can print sentry.status and find out why we don't have the sentries we were expecting, e.g.:

try:
    lxd1_sentry = self.d.sentry['lxd'][1]
except KeyError, IndexError:
    print(sentry.status)  # or something

Would be nice to get a patch release of this in ppa:juju/stable if possible so it can be used in OSCI.

[marcoceppi]

LGTM ⛵