Fixes #14

Allow defining multiple ports on the same exposed port but with
potentially different external mappings (for example to expose the same
port on more than one interface of the host, but not all interfaces).

Signed-off-by: Maxime Petazzoni <max@signalfuse.com>
Set detach to True when creating containers

Signed-off-by: Maxime Petazzoni <max@signalfuse.com>