Modify name display on posts in the front-end

[sophiefeng18]

If the user chooses to post anonymously, change their name display on their post to "Anonymous User"

Estimated effort for each task: medium
Dependencies among tasks: #14
Milestones to indicate which sprint the issue should be completed in (Sprint 1, Sprint 2, Stretch): Sprint 1
Acceptance criteria that describes how you know this task is done - think about how you will test this feature: Write tests so code passes all the tests.