corrected local_independencies method. Earlier it was showing duplicate variable in event1 and event2 [fixes #158]
adds __str__ and __repr__ methods for Independencies and IndependenceAssertion class
adds __str__ and __repr__ methods for Independencies and IndependenceAssertion class [fixes #129]
Merge branch 'dev' of https://github.com/ankurankan/pgmpy into dev
Merge pull request #160 from ankurankan/dev

Fixes #129 and #158