uniter: test improvements

uniter: test improvements

* on unit death, lack of hooks is now only verified *after* the uniter has
  stopped (previously, it would have been possible to fail to detect an
  unwanted hook.
* some consolidation of repeated code
* direct verification of the correct functioning of config-get, which was
  previously lacking

and most importantly

* by actually setting a Service from which the config can be got, cause
  config-get to function correctly again

https://code.launchpad.net/~fwereade/juju-core/trivial-fix-config-get-context/+merge/129391

(do not edit description out of merge proposal)

[fwereade, 2012-10-12 11:29:11]

Please take a look.

[rog, 2012-10-12 11:44:18]

On 2012/10/12 11:29:11, fwereade wrote:
> Please take a look.

LGTM

[fwereade, 2012-10-12 11:49:03]

*** Submitted:

uniter: test improvements

* on unit death, lack of hooks is now only verified *after* the uniter has
  stopped (previously, it would have been possible to fail to detect an
  unwanted hook.
* some consolidation of repeated code
* direct verification of the correct functioning of config-get, which was
  previously lacking

and most importantly

* by actually setting a Service from which the config can be got, cause
  config-get to function correctly again

R=rog
CC=
https://codereview.appspot.com/6656051