Added zca_whitening option to smallnorb.
Added zca_whiten option to mnist and smallnorb.
Tidied ZCA whitening code

Removed redundant functions, fixed whitespace.
Merge branch 'master' into zca
Added global normalisation and ZCA whitening to table_datset
Completed global normalisation and ZCA whitening
Fixes to ZCA whitening
Changed parameter names for smallnorb
Merge branch 'master' of github.com:rosejn/torch-datasets