Allow specifying replica count for service

[tnozicka]

OpenCompose user should be allowed to specify number of replicas for the service to be able to scale it.

Proposal: Add an optional field named replicas into ServiceSpec. It defaults to value 1 and it should map into generated deployment under DeploymentSpec.replicas

[surajssd]

I would like to work on it :)

[kadel]

Proposal: Add an optional field named replicas into ServiceSpec. It defaults to value 1 and it should map into generated deployment under DeploymentSpec.replicas

This might be a little bit more trickier. I don't think we should default to 1.
If replicas is not set in OpenCompose file, than it should be also unset in generated PodSpec.

Replica count might be different on the server from what is specified in OpenCompose file.
If you default to replicas: 1 it will always overwrite replica number when doing kubectl apply.
In some cases this might cause problems (for example when using AutoScaler)

I think replicas in OpenCompose should directly map to PodSpec. If it is unset, than it shouldn't be set in PodSpec. If it is explicitly set to 0 than also in PodSpec should be 0.