Update to fix issue with Ruby 2.1.1

- Removing two return values that were being used in blocks giving
(LocalJumpError: unexpected return) errors from Ruby and causing the
tests to fail.

- Update travis.yml to include Ruby 2.1
Rename scope :public to :publicly_visible

As of
https://github.com/rails/rails/commit/815c9deae8de557688e1c99aabe30454bcbe5970
scopes can no longer be named 'public', therefore the 'public' scope is
now called 'publicly_visible'.