Combine Text Pipeline with Object Pipeline

[anishapai]

For Prediction, there are currently two pipelines:

• a text pipeline, in which the models process string objects
• an object pipeline, in which the models process 'file' objects

The /predict endpoints also take in different parameters. We could combine these endpoints so that all uploaded files go through the same endpoint and are processed from there.

This would involve:

• Thinking carefully about how to maintain all the text functionality, e.g. authors, audience, source
• Considering if this is even necessary? Maybe it is decided that they should stay separate. How will the front-end accommodate this?
• Perhaps creating helper functions that process the uploaded files according to their type
• Being wary of keeping the create_new_prediction function readable, and concise

[anishapai]

This was done already by @barenla !! :)