Dockerfile to create a [Faasd](https://github.com/openfaas/faasd/) image.

While Faasd can't run in a container, this image **can** be imported into
[ignite](https://github.com/weaveworks/ignite) which runs it in a 
[firecracker](https://firecracker-microvm.github.io) microvm.

In this way resource usage of Faasd and all "lambdas" in it is capped
by the VM resources, and the rest of the system is sort-of-protected
by the VM sandbox.