Commands: remove dead code and pass err to callbacks.
Docker RunWrapper: add support for more configuration, name the containers.

* Refactor .start() to avoid code duplication, pass errors along
* Streamline .getFqn(), return .image option directly if present
* .createContainer()
  * Add options.service.create to defaults
  * Name the container based on the service name
  * remove named container if it already exists
* .runContainer()
  * Add options.service.start to defaults
  * Remove some options that didn't belong
  * Add NetworkMode default
Merge pull request #18 from geophree/improve-docker-support

Improve docker support