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`)

integration/vendor/github.com/docker/libcompose/lookup/composable.go

@@ -1,25 +0,0 @@
-package lookup
-
-import (
-	"github.com/docker/libcompose/config"
-)
-
-// ComposableEnvLookup is a structure that implements the project.EnvironmentLookup interface.
-// It holds an ordered list of EnvironmentLookup to call to look for the environment value.
-type ComposableEnvLookup struct {
-	Lookups []config.EnvironmentLookup
-}
-
-// Lookup creates a string slice of string containing a "docker-friendly" environment string
-// in the form of 'key=value'. It loop through the lookups and returns the latest value if
-// more than one lookup return a result.
-func (l *ComposableEnvLookup) Lookup(key, serviceName string, config *config.ServiceConfig) []string {
-	result := []string{}
-	for _, lookup := range l.Lookups {
-		env := lookup.Lookup(key, serviceName, config)
-		if len(env) == 1 {
-			result = env
-		}
-	}
-	return result
-}