Port BlobStorage sample into an official package

[blowdart]

And while we're at it, write a SQL one too.

https://github.com/GrabYourPitchforks/DataProtection.Azure/tree/dev/DataProtection.Azure

[pakrym]

Issues with Azure Key Vault:
0. Absence of netstandard version of package

1. How to sync distributed writes to secret?
2. More efficient ways of enumerating secrets then loading multi-part list and then getting each one by id.

[pakrym]

#163