This is the version of ruby that we're using for this gem
Loosen dependencies

We can allow a little slack in what versions of gems we use.
Use gemspec to specify dependencies

A nearly-empty Gemfile and no Gemfile.lock is the best practice.

Ref: http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/