ref(*): update bindle dependency and usage

[vdice]

This PR revs the Bindle dep up to the latest 0.8.0 version. In doing so, the following minimal set of updates were required:

• Update usage of the Bindle client API. In this PR, I went the route of only making strictly necessary updates, which includes a no-auth approach for satisfying the needs of the client instantiation. If reviewers approve, I would create a follow-up issue around actually implementing support for auth methods that the client supports.
• Add required fields to Invoice and Label objects
• Update the version for the itowlson/toast-on-demand test bindle to satisfy semver constraints that came in as part of the Bindle update (semver crate was rev'd to 1.0.4)

Thanks again to @itowlson who made it possible to update the Bindle version! (deislabs/bindle#287)

[itowlson]

Looks good to me! Thanks!