Postponed user actions on the platform

[satanio]

Huge data processing can take non trivial amount of time. We should think of a robust solution for this problem on the platform.
Example tasks: Large experiment data being processed with some statistical analysis, ugly model simulation.
We dont want the user to be left out hanging on some loading.
The task needs to fire, let the user do something else on the page, then notify him via notifications or email, show him the result.