fail fast on unknown options

[grosser]

prevents typos and makes the initializer easier to read + less hash lookups ... might do that for more methods later

needs ruby 2.0+ ... 1.9 was "end of life" February 23, 2015 ... and whoever still runs it will get an old version since it requires 2.0+

[grosser]

@gmmeyer

[gmmeyer]

@grosser can you address the rubocop failures?

[grosser]

fixed ... turned out rubocop was linting for 1.9 which did not have keyword args :)
... also changed rake to run rubocop so users see failures before making PRs

[grosser]

ready!

[grosser]

@gmmeyer merge ?