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/google/go-github/github/git_trees.go

@@ -30,6 +30,7 @@ type TreeEntry struct {
 	Type    *string `json:"type,omitempty"`
 	Size    *int    `json:"size,omitempty"`
 	Content *string `json:"content,omitempty"`
+	URL     *string `json:"url,omitempty"`
 }
 
 func (t TreeEntry) String() string {