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/spf13/pflag/bool.go

@@ -1,6 +1,9 @@
 package pflag
 
-import "strconv"
+import (
+	"fmt"
+	"strconv"
+)
 
 // optional interface to indicate boolean flags that can be
 // supplied without "=value" text
@@ -27,7 +30,7 @@ func (b *boolValue) Type() string {
 	return "bool"
 }
 
-func (b *boolValue) String() string { return strconv.FormatBool(bool(*b)) }
+func (b *boolValue) String() string { return fmt.Sprintf("%v", *b) }
 
 func (b *boolValue) IsBoolFlag() bool { return true }