add --single-replicas option support when new replicas field is specified

[Alejandro]

As a developer I want to update the behavior for --single-replicas according to the pr: https://github.com/RedHatInsights/clowder/pull/686/files that meet with:

• it deploys 1 replica when using a clowdapp resource which has minReplicas or replicas with a higher value, and --single-replica (or default value for it) is used.

[Brandon Squizzato]

Handled via #279