Create additional fake data when initializing a dev database

[elichad]

We don't create fake data for every model. This makes some things harder to experiment with locally, and also affects our ability to test the relevant pages for accessibility (mentioned in #2458). Here is a list of additional fake data that would be useful (with reason in parenthesis). This may expand over time.

• [ ] Event with a hard-coded slug (a11y tests)
• [ ] Organization with a hard-coded domain (a11y tests)
• [ ] Instructor recruitments & signups (a11y tests)

[maneesha]

@elichad recommends making this low priority and addressing models as they come up.