Move generators to their own namespace

* Move generators to their own namespace
* remove `gen-` prefix from generators
* s/vec/vector in vector generator
Merge pull request #5 from reiddraper/feature/generators-in-own-namespace

Move generators to their own namespace
WIP for review: add reporting via clojure.test integration (gh-2, gh-4)
WIP add defspec macro for defining clojure.test test vars for a property (gh-4)