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/lookup/envfile.go

@@ -0,0 +1,31 @@
+package lookup
+
+import (
+	"strings"
+
+	"github.com/docker/docker/runconfig/opts"
+	"github.com/docker/libcompose/config"
+)
+
+// EnvfileLookup is a structure that implements the project.EnvironmentLookup interface.
+// It holds the path of the file where to lookup environment values.
+type EnvfileLookup struct {
+	Path string
+}
+
+// Lookup creates a string slice of string containing a "docker-friendly" environment string
+// in the form of 'key=value'. It gets environment values using a '.env' file in the specified
+// path.
+func (l *EnvfileLookup) Lookup(key string, config *config.ServiceConfig) []string {
+	envs, err := opts.ParseEnvFile(l.Path)
+	if err != nil {
+		return []string{}
+	}
+	for _, env := range envs {
+		e := strings.Split(env, "=")
+		if e[0] == key {
+			return []string{env}
+		}
+	}
+	return []string{}
+}