Clojurians Log v2

I started working on the DSL. It's the one piece that would make using Vrac a breeze. I haven't communicated it clearly, but the Vrac library v0.1.0 which was released Monday is supposed to be used as a runtime, a target for the DSL compiler, but it is still "kind of" usable for the end users.

I have no prior experience transforming an AST, so if you see something in the code that could be better, do not hesitate to leave some comments on the Github commits.