Upload time API.
Improve tests and UTC handling.
Merge pull request #69 from frankban/upload-time-api

Upload time API.
Bundle validation: verify with charms.
Do not use the blobstore to retrieve the bundle charms.
Return the list of bundle verification errors in JSON format.
Improve comment in bundleCharms.
Improve docstrings.
Fix the bundleCharms method and provide unit tests.
Fix typo in export_test.go filename.
Minor fixes to the bundleCharms method.
Merge pull request #70 from frankban/bundle-verify-charms

Bundle validation: verify with charms.

Validate the bundle with respect to charms in the store.
internal/blobstore: use names, not hashes
internal/charmstore: use names, not hashes.
use blob names instead of hashes

We can't use content addressing with juju blob store,
as discussed ad nauseam online.
internal/v4: remove unnecessary method