Charm store API proposal, new version

[roger peppe]

Based on feedback from Rick Harding, amongst others,
we have made some changes to the proposed charm
store API. The new document is here:

https://docs.google.com/a/canonical.com/document/d/1TgRA7jW_mmXoKH3JiwBbtPvQu7WiM6XMrz1wSrhTMXw

The most significant change is that all endpoints
refer just to a single charm or bundle, rather than
being "bulk" calls as they were before. The /meta
endpoint now returns a list of all possible metadata,
and there's a new "any" endpoint that provides
the previous functionality of /meta.

There's also a facility for the storage of arbitrary
metadata to be associated with a charm or bundle
(the extra-info metadata endpoint).

  cheers,
    rog.