Add new db impl for Codax

[oubiwann]

Having Redis be a dependency is turning out to be a little bit of a pain, as I write blog posts on different machines, and may or may not have docker installed or running or all the images downloaded, etc. For something that's just tracking state between builds for local usage, there's no reason not to have a Clojure-embedded DB with file persistence.

Enter Codax.

Dev tasks:

• Add Codax as deb
• Create impl namespace for new work
• Implement DBConnector protocol for Codox
• Implement DBQuerier protocol for Codox
• Update configuration to use new backend
• Perform a full ingest of historical blog posts, crunch the data, and persist to data store