[+] Add some initial implementations of entities.

[ScottCTD]

Summary

• I implemented most entities as specified in our CRC model.
• Refer to issue #4

[ScottCTD]

Do we still need the UserFactory and stuff like that Also, if we merge this thing up right now, how do I ensure my next pull request can be thrown on this? Do I cherry pick on my own branch with the database loading thing

1. No. 2. You don't need to ensure.