A new user-focused API

[bfirsh]

An implementation of #1086.

Todo

• Thorough unit tests for new API
• Add run options which span both create and host config (e.g. ports and volumes)
• Full set of integration tests for containers
• Implement complete set of methods for images with integration tests
• Add remaining objects to new API
• Documentation
• Add docstrings
• Better service options?
• Handle image methods that apply to multiple tags on a repository.
• Squash commits a bit

Nice to have

• Better integration test cleanup
• CI for old Docker versions, (requires_api_version on integration tests, etc)
• Remove AutoVersionAPIClient in favour of just version='auto'?
• ImageNotFoundError instead of method on APIError
• Print a useful error if you call something that doesn't exist on Client, but does on APIClient.
• Implement imports for images
• Link to API documentation for each method

[shin-]

The only thing that's outstanding to me still is this thread: #1186 (comment)

But I think we can address it separately before the release. Let's go ahead and merge this. 👍

[bfirsh]

Yippee, thank you!