Current release uses deprecated /v1.11/ API

[bruienne]

The current API version in docker.coffee is fixed at 1.11 (https://github.com/awvessel/vessel/blob/master/src/app/ipc/docker.coffee#L13) which causes an error with the current 1.7.1 client in recent CoreOS alpha builds. Manually changing the API version to 1.19 resolves the issue for me. It may be necessary to determine which API version is the correct one given the CoreOS build being used or possibly just watch for "API too old" messages and stepping up the API version to the next milestone to be able to continue.