Upgrade to RSpec 3.1 and Rubocop 027.1

* implicitly require spec_helper
* randomize specs
* display verbose spec output when running just one spec

close #57 (issue)

close #63 (PR)
Add .ruby-version and .ruby-gemset to .gitignore

Folks who use those files to manage their gemsets can do so without git
offering to stage those files. h/t @vraravam
Adding Vine support.

close #65 (PR)
close #50 (Issue)
Add support for vimeo channel urls

close #64 (PR)
close #37 (Issue)
Keep track of the sites a little more implicitly

You still need to add the require line, but no longer need to register
the class in the list of classes.