Capability to publish shareable/re-useable models

[newton1985]

Describe the user role
As an oSPARC user, I would like to be able to share and/or re-use machine previously trained machine learning models.

Describe the goal
To give my trained networks to others, and/or pass them between services in my own projects.

Describe the benefit
This would speedup the development of new machine learning pipelines, and boost those pipelines that could benefit from transfer learning.

Additional context
Refers to #332