Buckets!

[loganlinn]

This adds the notion of buckets to poky alongside a few other changes and fixes.

• Update schema to include bucket varchar
  • Add created_at and modified_at timestamps (TODO add update trigger)
• Update KeyValueProtocol to include bucket paramter before key
• Remove RDMSKeyValueStore protocol, it was an uneeded abstraction
• Remove unused poky.kv.jdbc.pg-json
• Move poky.kv.jdbc.text to poky.kv.jdbc; will update poky.protocol.**.text namespaces too
• Fix jdbc mget; parens weren't correct & didn't generate k-v pairs
• Make the S & M servers in repl_helper delay objects to prevent instantiation while parsing/evaluating. They depend on environment variable DATABASE_URL and caused lein check to fail if it wasn't set.
• Various trailing whitespace cleanup