Parse docker run flags to allow non-detached containers

Added a basic check for the `-d` flag.
If it's present. Create container, add network, echo container ID
If not, add it, create container, add network and attach
Fixes #44

Signed-off-by: Dave Tucker <dave@socketplane.io>
Merge pull request #46 from dave-tucker/bug/44

Parse docker run flags to allow non-detached containers