Adds users migration, user & post seeder. Adds styling, base model.

** Update your .env.local.php file with new values after the merge **
- Add new values to env-template.php
- Add bootstrap styling and user-facing links
- Add BaseModel with constructor and accessors and mutators
- Add CSRF requirement to all models that extend BaseModel.
- Add user migration and user seeder
- Add post seeder