Add --publish
Use barrier.Forward
Make async errors cause container teardown
Forward Container.Failure to Container.Closing
Remove dying barrier from NewContainer
Merge pull request #9 from scraperwiki/port-spec

Implement specifying which ports are forwarded where
Merge branch 'use-forward'

Conflicts:
	main.go
Increase information in errors

In particular, give error when it fails to call iptables
Build instructions
Read various enviornment variables for sockets

Same as boot2docker sets for the docker client to use.
Merge pull request #16 from scraperwiki/use-docker-env

Read env variables for sockets; README improvements
Implement notion of different image sources
Enable update signal over localhost HTTP API
Make Run/Build take the UpdateEvent
Add OutputStream and BuildComplete to UpdateEvent
Send build result over HTTP request
Implement BuildTarballContent
Flush every line during build
Ignore /iptables
Support zip uploads