Properly handle the data-mean during PCA

Eigenface decomposition requires us to center the data (i.e. subtract the
data-set mean) *before* running singular value decomposition. RandomizedPCA
already does this, so we don't have to do it here:
https://github.com/scikit-learn/scikit-learn/blob/7426e6a274/sklearn/decomposition/pca.py#L582-L584

Reported by @PetterS:
- https://github.com/c-w/github-data-challenge-2014/commit/d264330#commitcomment-8703627
Re-generate eigenfaces (PCA data-mean fix)