Add support for Clojurescript

Many changes were done in order to accomplish this, however the core library
still intact. The following changes were done:

* Rename monads.test.core to monads.test.core-tests to be
  easily identified on open buffers (not having to explore the path
* Move the do macro to monads.macro namespace
* Add dev-dependencies and plugins:
  - lein-cljsbuild
  - lein-dalap
  - buster-cljs
* Test suites run successfuly both in JVM and in Javascript (including optimized version)
* Add .travis.yml automated test
* Remove reify usage because of strange bugs in cljs