Added HierarchicalMultilabelModel class
Modified HierarchicalMultilabelModel:
    * Changed get_attr_vector -> get_label_vector
    * Minor refactorings in tests and source code
Merge pull request #2426 from abinashpanda/develop

Added HierarchicalMultilabelModel class
Minor fixes to mmd notebook.
EM base class added
mixture model class structure
Merge pull request #2446 from mazumdarparijat/em

EM base class added
Merge pull request #2442 from mazumdarparijat/kdensity

class structure for mixture model added
updated data to merge of ANPR notebook data
ANPR notebook added
tweaked findcontours
addded a try catch for import cv2
Merge pull request #2384 from kislayabhi/anpr

ANPR notebook added
added graphcuts python examples