WIP: Bump Clojure and Midje and upgrade to Lein 2.

Hey Man, this is suuuper minor, but right now the midje-cascalog dep in forma-clj seems to pull in Clojure 1.3.0 and make it default. Like if you fire up Emacs, open forma-clj, and connect to a REPL server, a `(clojure-version)` will give you 1.3.0. If you remove the midje-cascalog dep, you get 1.4.0. I can't seem to override it to 1.4.0.

Basically we want 1.4.0 for that little `integer` function that boxes ints and avoids auto-coercion to Long. This came up in that [forma-clj PR](https://github.com/reddmetrics/forma-clj/pull/320).

Not sure if this is the right way to do modify midje-cascalog to get 1.4.0, but I [pushed it up to Clojars](https://clojars.org/eightysteele/midje-cascalog) and it's working nicely in forma-clj. If there's a better way to patch, let me know and I'll update this PR for sure.