Reimplement the azure objstorage on top of recent azure-storage-blob
The new version is what Debian unstable is carrying, so use that. Unfortunately the situation with respect to the old API hasn't been clarified by upstream yet.
https://github.com/Azure/azure-storage-python/issues/655
Test Plan
toxed, and also ran the tests on a real azure storage account
Migrated from D3116 (view on Phabricator)