Oras-py Release v0.1.0

What's Changed

• Remove Client by @vsoch in #59
• Fix bug that path provided can be posixpath
• Move client to be more robust examples, with external examples too
• Clear instructions for using debug
• Addition of "set_token_auth" to main function is a token is supported (rare I think)
• external login functions refactored to be part of the main client to simplify design
• registries allow namespaces that don't perfectly conform to a traditional docker URI, and we now allow that
• logout properly unsets any token or auth credential
• if an initial try of an authentication fails, we fall back to trying providing just the credentials verbatim (EC2 seems to need this)
• blob names can be provided with an optional mediaType separated by a colon (e.g., path/to/blob.png:my.custom.mediatype.
• Annotations can actually be "None" (again, EC2)

See #59 for detail about the reason to remove the client.

Full Changelog: 0.0.18...0.1.0