Backend project structure

[oli-lane]

Right now, the backend is set up to have all of the routes in api/app.py. In order to make it more scalable, make the routes modular. Here is a file structure you could use:
api/
|-- src/
|----| app.py
|----| routes/
|------| __init__.py
|------| slo_county.py

Requirements:

• Create a Chalice Blueprint in slo_county.py
• Create a dummy route in slo_county.py that returns "Hello World!"
• Register the blueprint in app.py
• Test the new route (use curl in command line)

As always, make sure to run the linter and formatter and make sure everything works when you run locally!