Extract providers to their own package

This is just doing that and making it compile :)

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

provider/etcd/etcd.go

@@ -0,0 +1,37 @@
+package etcd
+
+import (
+	"fmt"
+
+	"github.com/containous/traefik/provider"
+	"github.com/containous/traefik/provider/kv"
+	"github.com/containous/traefik/safe"
+	"github.com/containous/traefik/types"
+	"github.com/docker/libkv/store"
+	"github.com/docker/libkv/store/etcd"
+)
+
+var _ provider.Provider = (*Provider)(nil)
+
+// Provider holds configurations of the provider.
+type Provider struct {
+	kv.Provider `mapstructure:",squash"`
+}
+
+// Provide allows the etcd provider to Provide configurations to traefik
+// using the given configuration channel.
+func (p *Provider) Provide(configurationChan chan<- types.ConfigMessage, pool *safe.Pool, constraints types.Constraints) error {
+	store, err := p.CreateStore()
+	if err != nil {
+		return fmt.Errorf("Failed to Connect to KV store: %v", err)
+	}
+	p.Kvclient = store
+	return p.Provider.Provide(configurationChan, pool, constraints)
+}
+
+// CreateStore creates the KV store
+func (p *Provider) CreateStore() (store.Store, error) {
+	p.StoreType = store.ETCD
+	etcd.Register()
+	return p.Provider.CreateStore()
+}