Merge branch 'master' of https://github.com/juju/juju
Merge branch 'master' of https://github.com/juju/juju
Merge branch 'master' of https://github.com/juju/juju
Merge branch 'master' of https://github.com/juju/juju
KVM containers can now be created using a user-provided SimpleStreams URL as a base.
Apt-get upgrades are now optional.
Corrections from round #1 of reviews.
Corrections from round 2 of reviews.
Fixed nil-reference panic.
Modified test to reflect new default of preferring updates/upgrades.
Merge pull request #584 from katco-/lp-1322302-local-slow-transition-part-2

Configurable apt-get behavior.

For:
https://bugs.launchpad.net/juju-core/+bug/1322302
https://bugs.launchpad.net/juju-core/+bug/1350493