Add support to build docker-compose on ARM 32bit
Add support to build docker-compose on ARM 32bit

Added a new Dockerfile (Dockerfile.armhf) specific for ARM 32 bit.
The Dockerfile was updated compare to default one:
  - Base image is armhf/debian instead of debian
  - Docker binary is downloaded with the correct arch (although it does not
    seems to be used)

Signed-off-by: Jean-Christophe Berthon <83beaa127e1b3445d82132c8518f2623c59a7c33@berthon.eu>

sdurrheimer/compose,schmunk42/compose,thaJeztah/compose,funkyfuture/docker-compose,michael-k/docker-compose,sdurrheimer/compose,thaJeztah/compose,shin-/compose,jrabbit/compose,hoogenm/compose,schmunk42/compose,vdemeester/compose,funkyfuture/docker-compose,swoopla/compose,vdemeester/compose,hoogenm/compose,dnephin/compose,swoopla/compose,jrabbit/compose,shin-/compose,michael-k/docker-compose,dnephin/compose