Rename resource methods to mimic Ruby on Rails ActiveRecord naming conventions

[tdstein]

In #16, we choose method names for the resource implementations (e.g., find, find_one, create) using our best guess at the time. Since then, I have realized that our implementations mimic the Ruby on Rails ActiveRecord API in many ways. Since Ruby on Rails is battle-tested, I feel confident that mimicking the ActiveRecord API through the following migration will result in a more approachable API.

Rename the following methods:

• find -> find_by
• find_one -> first
• delete -> destroy
• get -> find*

*The find method is unique because it continues to exist, but the functionality will completely change.

These methods are not impacted:

• count
• create
• update