'compare' can be one of equal, not-equal, match or non-match.

'value' is either a fixed string for (in)equality tests, or a
regex to test for (non-)match.

This makes it possible to set values for the invocation via env
variables in the pod template, in particular to use PROXY.

This has required the introduction of pkg/interfaces, defining an
interface for Service Event generation, so that the Varnish controller
can hold a reference to IngressController, without introducing
import cycles for pkg/varnish and pkg/controller.

This has brought in a refactoring of controller/worker, introducing
the SyncObj to pass into the queue to workers. Now workers don't
have to guess at whether they're adding, updating or deleting.

And remove some dead code while we're at it.

Some elements were changed to be unexported, since they didn't need
to be exported or publicly documented.

cmd/ now only contains main.go.

And update docs for self-sharding as configured by VarnishConfig.

This adds the client API for the Custom Resource in the group
ingress.varnish-cache.org, with generated code for the API.

Also adds the pkg/ path to the project, and moves the Makefile up
to the root directory, so that code builds in pkg/ and cmd/.

Enables out-of-cluster runs.