Add support for scaled services

[aaudiber]

Currently, the project is unable to run docker-compose files which use the scale parameter, e.g.

services:
  worker:
    scale: 5

Things break because now looking up the service "worker" will find 5 different container IDs. My current workaround is to copy the "worker" section 5 times under "worker1", "worker2", etc.

To work with scaled services, the code needs to be updated to differentiate between service names and container names. Is this feature something the project would be interested in? If so I could take a crack at the implementation.

[dotCipher]

Apologies on the delayed response, but we welcome any submissions. Feel free to take a crack at the implementation and include tests :)