Implement update-service operation in firecamp-service-cli

[jazzl0ver]

It would be greate to have update-service operation in the cli tool to manage amount of replicas, volumes size, heap size, etc

[JuniusLuo]

yes, updating the service and scaling the service will be supported. Increasing the volume size would be a separate feature.

[cloudstax]

Updating cassandra heap size and scaling up cassandra service are supported in 0.9.2 release. Updating other configs and scaling other services will be supported in the later release.