changed __init__.py to import BayesianModel, Factor and Exceptions subpackage
modified __init__.py to import BayesianModel class directly
modified __init__.py to import BayesianModel class directly
modified __init__.py to import Factor class directly
modified __init__.py to import all the Exceptions directly
changed pgmpy.Exceptions -> from pgmpy import Exceptions
changed pgmpy.Exceptions -> from pgmpy import Exceptions
added import statement in all the examples