Code review comment for lp:~frankban/juju-quickstart/distro-only-flag

*** Submitted:

Add the distro-only flag.

This can be used (e.g. in trusty) to
prevent quickstart from installing
the Juju stable PPA.

Tests: `make check`.

No QA required, I already tested this on
a trusty VM.

R=rharding
CC=
https://codereview.appspot.com/81400043

https://codereview.appspot.com/81400043/