Code review comment for lp://qastaging/~frankban/juju-quickstart/version-handling

*** Submitted:

Improve version handling.

Modify the app.ensure_dependencies function
so that it returns the Juju version tuple.
This way we allow for reusing the version
through the app and we can avoid calling
"juju version" multiple times.

Support local environments by installing
the juju-local meta-package in place of
specific packages (e.g. lxc, mongo).
This way we don't have to update quickstart
if core devs introduce new local env
dependencies.

Fix the destroy-environment message displayed
at the end of the process. The -e flag is
included when an old Juju is used.

Tests: `make check`.

QA: no strictly required.
Use .venv/bin/python juju-quickstart, check everything
works well, check the destroy-environment message
at the end of the process.

R=rharding, matthew.scott
CC=
https://codereview.appspot.com/74010044

https://codereview.appspot.com/74010044/