Configure fastly cleanup

[cwillisf]

Changes:

• Convert routes.json to routes.js and move conditional logic into that shared file so that all scripts that process routes can be on the same page (heh) about what routes exist. For example, webpack and configure-fastly.js will now always see the same routes given the same environment variables.
• Rebuild fastly-extended.js with correct JSDoc type hints
  • Note that the type hints in node_modules/fastly/lib/index.js are malformed. Newer versions are correct, but present a VERY different API.
• Fix error handling in configure-fastly.js and friends
  • the async library expects Error objects, not strings
  • some call-sites were passing err, res style arguments to a function that only takes err
• Add a mocking & logging setup for Fastly API requests

These changes should make it easier to understand our routing and Fastly configuration, but should not cause any significant difference in the actual configuration.

This is the foundation for an upcoming functional change to configure-fastly.js

Test Coverage:

I ran this locally and the output seems reasonable, but I'd need to compare it to the real Fastly configuration to be sure. On the plus side, this will provide a baseline so it's easier to tell in the future if a change has affected the configure-fastly.js output. Existing tests pass.