Shore up unit tests [ongoing]

[jaybobo]

• Audit model specs.
• Add tests for any untested public methods

Use pry, factory_girl & rspec.

Ex. https://github.com/paircolumbus/pairs2/blob/master/app/models/user.rb#L24

Helpful links:
https://www.relishapp.com/rspec/rspec-mocks/docs
https://github.com/rspec/rspec-expectations#built-in-matchers