Fix marathon TLS/basic auth

[emilevauge]

This PR fixes Marathon TLS/basic auth.
It also adds DCOS token support.

Fixes #365

Signed-off-by: Emile Vauge emile@vauge.com

[vdemeester]

@emilevauge I think tests need updates 👼

# github.com/containous/traefik/provider

provider/marathon_test.go:115: cannot use fakeClient (type *fakeClient) as type marathon.Marathon in field value:

    *fakeClient does not implement marathon.Marathon (missing ApplicationByVersion method)

provider/marathon_test.go:199: cannot use map[string]string literal (type map[string]string) as type *map[string]string in field value

provider/marathon_test.go:218: cannot use map[string]string literal (type map[string]string) as type *map[string]string in field value

provider/marathon_test.go:237: cannot use map[string]string literal (type map[string]string) as type *map[string]string in field value

provider/marathon_test.go:256: cannot use map[string]string literal (type map[string]string) as type *map[string]string in field value

provider/marathon_test.go:275: cannot use map[string]string literal (type map[string]string) as type *map[string]string in field value

provider/marathon_test.go:295: cannot use map[string]string literal (type map[string]string) as type *map[string]string in field value

provider/marathon_test.go:314: cannot use []*marathon.HealthCheck literal (type []*marathon.HealthCheck) as type *[]marathon.HealthCheck in field value

provider/marathon_test.go:338: cannot use []*marathon.HealthCheck literal (type []*marathon.HealthCheck) as type *[]marathon.HealthCheck in field value

provider/marathon_test.go:365: cannot use []*marathon.HealthCheck literal (type []*marathon.HealthCheck) as type *[]marathon.HealthCheck in field value

provider/marathon_test.go:365: too many errors

FAIL    github.com/containous/traefik/provider [build failed]

[emilevauge]

@samber @vdemeester Finally green 🎉

[vdemeester]

Yay 😇
LGTM 🐮