EOD update

[Ian Booth]

Hi

I'm not sure if these will get reviewed in time to make the next Go juju
release. If they do, I'll land later tonight after soccer.

tl;dr; Fix error with "juju destroy-environment" on Openstack instances. With
this change, HP Cloud support should be nice and hassle free for users.

Goose MP:

https://code.launchpad.net/~wallyworld/goose/retain-trailing-slashes/+merge/154876

The goose changes ensure trailing "/" are not stripped off the URLs. This was
causing deletion of (pretend) directories (files ending in "/") to fail.


juju-core MP:

https://code.launchpad.net/~wallyworld/juju-core/openstack-destroy-error/+merge/154877

The final delete container is put in a shortAttempts loop to allow for eventual
consistency.