Add documentation tests

This adds a new suite of tests, ensuring that all public mappings (that are not on the exception list) provide docstrings.

Please note that this commit will fail the Codeship build, seeing how providing documentation will be a seperate commit (soon to come.)
Add docstring to `tip.parser`

Please note that this commit also addresses the terrible naming of `tip.parser/grammar`, which is now `tip.parser/parser`. It was probably not the time or place to do it, but now at least our suffering has come to an end.
Clean up `tip.parser`

This edition uses the prettier docstring available for `def` as of Clojure 1.3, and also removes the rather pointless definition of `ebnf`. If it becomes needed, it can easily be reintroduced.
Merge pull request #12 from tidbytes/feature/11-documentation-tests

Test for docstrings for public mappings