changing the simplestreams filename format

[Curtis Hovey-Canonical]

The metadata file name is arbitrary, though it follows a convention
published by other tools we do not control. Looking at
    https://streams.canonical.com/juju/tools/streams/v1/index.json
The path is just a relative location on disk to load.The content of
that file doesn't need to change.We have 100% control juju tool steams

image stream is only under our control for private clouds created with
our metadata plugin. We cannot change the names at
    http://cloud-images.ubuntu.com/releases/streams/v1/index.json
because there are other users of this data.

I think the sync-tools command is safe because it only works with
tool. Anything syncing images on windows will need to recreate the
metadaya...or we escape the colons on windows machines. Do we have
some support for this already? I can see names are escaped in the
env's control-bucket.





-- 
Curtis Hovey
Canonical Cloud Development and Operations
http://launchpad.net/~sinzui