Replace antlr4 deps with antlr4-runtime

[namenu]

The ANTLR used in the parser is a very large and heavy library, taking up around 50MB when unjarred.
This makes it difficult to use Lacinia easily with AWS Lambda, etc.

Therefore, I propose to replace ANTLR with the antlr4-runtime dependency rather than the whole thing. To do this, clj-antlr needs to be removed and pre-generated java code should be interop-ed instead.

[namenu]

I've worked on it here green-labs#6 and it works well in our fairly complex schema.
I'd be interested to know what you think! @hlship

[hlship]

I'm very interested in this; it's just a bit big for a bug fix release, so it'll wait for 1.3 rather than 1.2.x.
I don't mind mixing a little bit of Java into my lovely Clojure code ... if there's a big payoff!