experimental implementation of the proposed push specification for ACIs

See appc/spec#418 for details of the proposed specification.

It takes as input an ACI file, an ASC file, and an App Container Name (i.e. quay.io/coreos/etcd). Meta discovery is performed via the provided name to determine where to push the image to.

See acpush --help for details on accepted flags.

Building acpush requires go to be installed on the system. With that, the project can be built with the following commands:

go get -d github.com/appc/acpush
go build github.com/appc/acpush

acpush reads rkt's config files to determine what authentication is necessary for the push. See rkt's documentation for details on the location and contents of these configs.