Dockerfile: use Alpine 3.2
Dockerfile: use Alpine 3.2

CiscoCloud/marathon-consul,trueanthem/marathon-consul,ojagodzinski/marathon-consul,ojagodzinski/marathon-consul,allegro/marathon-consul,pawelszymczyk/marathon-consul,shopkeep/marathon-consul,trueanthem/marathon-consul,shopkeep/marathon-consul,guilhem/marathon-consul,CiscoCloud/marathon-consul,pawelszymczyk/marathon-consul,allegro/marathon-consul,guilhem/marathon-consul