Create an endpoint to get user's chosen home chapter.

[tasomaniac]

Currently we have a PUT request to /frisbee/user/home which stores users home chapter. I doesn't actually work. Even if it works, we currently don't use it.

• First we should remove frisbee name from the endpoint.
• Second, we should have a GET request to read the value.

[tasomaniac]

This is also related to gdg-x/firefly#86
After this is done, clients can use signed-in user's home chapter to automatically fill the UI.