Implement the store.AddBundle method.
Also implement a cstomized CharmURL type so that
we can easily deal with partial URLS.
Restore original dependencies.
Update dependencies file.
De-duplicate bunlde charm URLs. Improve serialization tests.
Improve marshal tests.
Merge pull request #28 from frankban/add-bundle

Implement the store.AddBundle method

Also implement a cstomized CharmURL type so that we can easily deal with partial URLS.

Updated dependencies so that we are now using the updated names/charm.v2 packages.
internal/v4: resolve ids
fixes after rebase