ML related improvements

[DiegoPino]

What?

Experimental for 0.9.0 ML related improvements. Few ones are:

• Score Processor/field that helps with analyzing based on a model the actual number output. This is very specific to face detection given that the similarity score is a function with ranges and not a direct Cosine of vectors.
• Allow one ML model's Annotations to become input (like a pager) for other ML Models
• Allow Ajax Filters for ML image similarities to be saved on a SESSION so Ajax facets can use/re-use them on a different call. Or we can base64 encode the region as an URL argument?