Implement Angular mock API.

This issue tracks the progress of setting up a basic mock API.

Why implement a mock API?

The Java API is in a state of constant development, so it cannot be relied on for development of the client. Development of the client and server should be separate, so, consequently, it is typical for a mock API to be built to allow work on the client to continue. As a bonus, such mock APIs are often useful for unit tests.

To close this issue, we must:

• Build a mock API that allows us to GET, POST, PUT, and DELETE data. The changes should be persistent across subsequent calls, but not necessarily across page reloads (for v1)
• Have a system in place to easily add, delete, and modify our mock endpoints
• Have a single example of using a mock endpoint in an Angular directive

@carldanley is on this one.

should be used to check off accomplished sub-tasks.