added check_assumptions in main namespace
added check_assumptions in main namespace

Added check_assumptions() in main namespace by adding it in _init_.py.

souravsingh/sympy,sampadsaha5/sympy,postvakje/sympy,aktech/sympy,skidzo/sympy,kaushik94/sympy,chaffra/sympy,aktech/sympy,souravsingh/sympy,yashsharan/sympy,kaushik94/sympy,souravsingh/sympy,postvakje/sympy,postvakje/sympy,skidzo/sympy,sampadsaha5/sympy,madan96/sympy,jaimahajan1997/sympy,aktech/sympy,kaushik94/sympy,chaffra/sympy,jaimahajan1997/sympy,skidzo/sympy,jaimahajan1997/sympy,madan96/sympy,sampadsaha5/sympy,yashsharan/sympy,madan96/sympy,chaffra/sympy,yashsharan/sympy