The conduit.io/* k8s labels and annotations we're redundant in some
cases, and not flexible enough in others.
This change modifies the labels in the following ways:
`conduit.io/plane: control` => `conduit.io/controller-component: web`
`conduit.io/controller: conduit` => `conduit.io/controller-ns: conduit`
`conduit.io/plane: data` => (remove, redundant with `conduit.io/controller-ns`)
It also centralizes all k8s labels and annotations into
pkg/k8s/labels.go, and adds tests for the install command.
Part of #201
Signed-off-by: Andrew Seigner <siggy@buoyant.io>