goose update required plus important juju-core changes

[Ian Booth]

Hi folks

If you run juju-core from source, you will need to grab the latest goose rev
(95) in order for the tests to pass.

The latest commits introduce some important changes, particularly for Openstack
deployments. The key highlight is that the new simplestreams (lp:simplestreams)
image metadata is used for image selection. With EC2, this change is
transparent. For Openstack, it means that there is no longer any need to use the
environment parameters default-image-id and default-instance-type. These were
deprecated in Py Juju and are now ignored for Go Juju.

Image metadata is automatically generated for Canonistack, and I have uploaded
image metadata for HP Cloud for image 81078 (precise, amd64). So long as your
public bucket URL is correctly configured, this image metadata will be found.
End users now no longer have to manually update their environments.yaml file
each time a new image id is required, or indeed know the image id in the first
place in order to start using Juju. For HP Cloud, we still need to get image
metadata for series besides precise/amd64 uploaded and figure out the process to
make it all maintained automatically like for EC2 and Canonistack.

As far as instance types are concerned, Go Juju for Openstack now supports using
constraints to figure out what to do, just like for EC2. So the need for the
Openstack specific, deprecated default-instance-type parameter is gone.

Just to be clear, the above changes have just landed so will only apply if you
run Go Juju from source.