Timezone has been added to the User resource in the API, this was a request.
The possible values of timezone are the timezone options available in the User settings page.
The User's timezone is queried along with the rest of the User's information in order to reduce the number of queries made to the database.

Accessed a list of Users (/api/users/) and a single user (/api/users/admin/) in order to confirm correct data (Local Review Board had 2 users total with different Timezones).
Performed a unit test to ensure that a minimal amount of queries are performed (when a User is queried, their profile is joined). 

Unit test consisted of starting with the "unoptimized" version (which made an extra query) and fixing until the data was retrieved without the extra query being made.