YAML configuration for Pipeline

[tanaysoni]

It would be a useful feature to represent Pipeline as a YAML configuration file.

We would need the following:

• schema for the YAML configuration
• save the configuration of an existing Pipeline instance
• load a new Pipeline using a YAML

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 21 days if no further activity occurs.

[Timoeller]

Saving of pipeline handled in #741
Rest is implemented, closing now.