[Finishes #81209776] Generated Community scaffold.
[Finishes #81210122] Bootstrap-ify the layout.
Add Community length and uniquness validation and associated model tests.
Generated Submission scaffold.
Added validation to submissions and updated views to link between submissions and communities.
Generated Comment scaffold.
Add comment validations, and clean up comment/submission related views.
Submission show page shows root comment and the comments' nested replies.
Added README.md with team photos.