Add a quick Gemfile so you can install test deps with Bundler

(I'm trying to figure out how to install rip -- its website with the
standalone installation instructions is gone now... but it seems like
switching to Bundler + gemspec would be reasonable at this point?)

[20 min later] ... yeah, this isn't going well. I'm going to remove
deps.rip. RIP rip.
Fix a ton of 'void context' warnings for free by just using better matchers
WIP message -  fix the rest of the warnings