Resolve some deployment blockers

[westonplatter]

@roy-pstr Thanks for sharing the repo. I used it as a starting point for deploy a service and ran across some small things I resolved to get it work on my setup. Maybe these changes are helpful for others.

Changes:

• docker: add PYTHONPATH to resolve module not found error
• docker: use dot syntax to refer to handler function
• docs: add note about architecture on macs vs other machines