Anonymous posting backend

[Nalseaf]

Modified src/posts/create.js file to initiate an anonymous value
then Modified to check for anonymity in the src/topics/posts.js file to then set the username and displayname to "Anonymous"

closes #6

[mthani2]

Looks like there is an issue with the db schema cause a failure in the node test. We need to update our schema definition in the test to include "anonymous".

This connects to issue #4

[sarrakhelifi-cmu]

I have seen the issues passed by in terms of Node, this definitly connects to what I've been working on with issue #4. I will be working on this now.

[mthani2]

Since this issue has the "help wanted" label, I will now be taking on this issue moving into sprint 2 making all the changes necessary to resolve issue #4 and issue #6, to progress towards closing the user story #2.

These changes will be made on the new branch 'anonymous-post-full-feature'.