Refactor traefik with package

Split a bit traefik into package. The idea behind this refactor is to
start move inter-dependencies away and do some DRY or SRP.

- Adds a `provider` package, with providers except `web.go`
- Adds a `types` package with common struct.
- Move `gen.go` to an `autogen` package

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

provider/provider.go

@@ -0,0 +1,7 @@
+package provider
+
+import "github.com/emilevauge/traefik/types"
+
+type Provider interface {
+	Provide(configurationChan chan<- types.ConfigMessage) error
+}