Tests & model-building

+ Removed test/unit
+ Added RSpec for testing
+ Wrote first unit tests based on [Location](https://github.com/codeforboston/urbanite/wiki/Location-Template-v3), [Event](https://github.com/codeforboston/urbanite/wiki/Event-Template-v3) templates
+ Wrote first sketch integration test
+ Updated `rake db:populate` to reflect model updates