Ensure correctness of faceness measure

[jakewilliami]

This is an adapted feature. I think I slightly misunderstood, and this needs to be corrected.
The faceness measure needs to be reviewed to ensure its correctness. It should be a feature of the cascade, which itself needs to be assessed.

[jakewilliami]

The difference in faceness scores between positive and negative images seems to be statistically significant after some changes, just using 1000 training images and 1000 testing images:

scores.pdf

[jakewilliami]

Could learn from this or this.