added CardinalityError in Exceptions.py
added CardinalityError in Exceptions.py

liquidmetal/pgmpy,vivek425ster/pgmpy,anaviltripathi/pgmpy,pgmpy/pgmpy,vivek425ster/pgmpy,jhonatanoliveira/pgmpy,yashu-seth/pgmpy,liquidmetal/pgmpy,kislayabhi/pgmpy,kislayabhi/pgmpy,pratyakshs/pgmpy,ankurankan/pgmpy,jhonatanoliveira/pgmpy,ankurankan/pgmpy,abinashpanda/pgmpy,khalibartan/pgmpy,abinashpanda/pgmpy,sandeepkrjha/pgmpy,khalibartan/pgmpy,palashahuja/pgmpy,sandeepkrjha/pgmpy,palashahuja/pgmpy,kris-singh/pgmpy,pgmpy/pgmpy,yashu-seth/pgmpy,kris-singh/pgmpy,pratyakshs/pgmpy,anaviltripathi/pgmpy