feat: add blockstorage capabilities

The client can now make calls to /storage/blocks endpoints of Deuce
FYI - I am trying to import the various types into deuceclient.api so Block is accessible as deuceclient.api.Block and we only need to import deuceclient.api to get access to it.

api_v1 and api_vault (L11-12) I believe go away in PR #16. Let's do the same with L15; L13-14 should go away with integration of PR #16 too.