Database seeds should include Events

[sandbergja]

User story

As a developer making a change to the events page, I would like to have some Events already existing in the database, so that the events page isn't totally empty.

Success criteria

• When I run rake servers:start, it adds 10 events to the database if they don't already exist
• I can confirm that the 10 events display on the events page

Implementation notes

You can add a single event if it doesn't yet exist with something like this:

Event.find_or_create_by(id: 12, start: '2020-10-10', finish: '2020-10-11', success: true)