Please merge master into your feature branches

[Ian Booth]

FYI for folks developing feature branches for juju-core.

juju-core master has been updated to include the first round of functionality to
improve the bootstrap experience. The consequence of this is that CI scripts
needed to be updated to match. This means that any feature branch which has not
had master commit 294388 or later merged in will not work with CI and so will
not be blessed for release.