Add command to include new pipeline elements via CLI

Problem

Currently, it's quite a manual task to add a newly developed pipeline element, e.g., adapter, data processor or data sink container into running StreamPipes environments.

Solution

Use CLI and add extra command called "add" which lets users easily add a new pipeline element service to the catalog of existing services. Additionally, users can specify wether they want to add this service to their current environment under .spenv.