This change adds a timer trigger API, client, and implementation. Users can trigger a function with a cron-compatible string.
This change also moves the publisher interface and webhook-based publisher implementation out of kubewatcher and into a separate `publisher` package.
When the request is handled successfully, json data is returned, this
patch changes the response Content-Type header from text/plain to
application/json
Fixes: #144
Environments for functions. For now this is just the image URL for the
function run container. In the future, Environments will also have
build container image URLs, and perhaps parameters to those
containers.
Create/read/update/delete/list. Versioning will be added later. For
now, only the latest update is stored.
This implemenents create/read/update/delete/list for http triggers.
This isn't quite the final implementation: you can't look up old
versions by UUID since it only stores the latest update. I'll get to
that later.
