Build a fuzzy server

[SamRoberts]

I don't really think fuzzy needs a service, but I intend to use fuzzy to experiment with setting up high-quality service infrastructure in various clouds, so I need some version of fuzzy to run in the cloud.

[SamRoberts]

First step: split fuzzy up into different projects, so I can add new service binaries without polluting the fuzzy lib / cli with unnecessary dependencies.

[SamRoberts]

Second and third steps: set up a fuzzy lambda executable and make it run fuzzy.

Before closing this issue, I need to:

• check this actually runs in a real AWS lambda environment,
• look into some simple tests for the lambda (and cli?) executables,
• rustdoc for lambda executable
• double check we have sensible behavior when the user submits invalid input. Not sure if we return a valid error or just hang at the moment.