Update traefik dependencies (docker/docker and related) (#1823)

Update traefik dependencies (docker/docker and related)

- Update dependencies
- Fix compilation problems
- Remove vdemeester/docker-events (in docker api now)
- Remove `integration/vendor`
- Use `testImport`
- update some deps.
- regenerate the lock from scratch (after a `glide cc`)

vendor/github.com/docker/libcompose/yaml/external.go

@@ -0,0 +1,37 @@
+package yaml
+
+// External represents an external network entry in compose file.
+// It can be a boolean (true|false) or have a name
+type External struct {
+	External bool
+	Name     string
+}
+
+// MarshalYAML implements the Marshaller interface.
+func (n External) MarshalYAML() (interface{}, error) {
+	if n.Name == "" {
+		return n.External, nil
+	}
+	return map[string]interface{}{
+		"name": n.Name,
+	}, nil
+}
+
+// UnmarshalYAML implements the Unmarshaller interface.
+func (n *External) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	if err := unmarshal(&n.External); err == nil {
+		return nil
+	}
+	var dummyExternal struct {
+		Name string
+	}
+
+	err := unmarshal(&dummyExternal)
+	if err != nil {
+		return err
+	}
+	n.Name = dummyExternal.Name
+	n.External = true
+
+	return nil
+}