Have posts marked as anonymous have the name and icon set to system default

[RyanChernoff]

Estimated effort:
This task will take a slight effort (Moderate) because the user ID, name, and profile picture have to be changed for anonymous posts to be a default generic icon and name.
Dependencies among tasks:
This task has a dependency on issue #6 because we need to be able to have the anonymous posting functionality working before we can hide aspects of the UI as a result of it.
Initial assignments for team members:
This task will initially be handled by Rathi.
Milestones:
This task should be completed by the end of Sprint 2.
Acceptance criteria:
We will test this feature by making tests on the UI where users make posts anonymous and see if all their information is actually hidden. We will check if when the anonymous option is clicked on the post creation page, all author info (profile and name) will be hidden from all users on the UI on that post.