This uses the Packet.net API and iPXE to boot a Moby host.
There are several enhancements coming soon, such as SSH key
customisation, but this PR is sufficient to boot a host and
then use the web interface to get console access.
The user must currently upload the built artefacts to a public
URL and specify it via --base-url, e.g.:
moby run packet --api-key <key> --project-id <id> \
--base-url http://recoil.org/~avsm/ipxe --hostname test-moby packet
See #1424#1245 for related issues.
Signed-off-by: Anil Madhavapeddy <anil@docker.com>