Revert "Use float.as_integer_ratio (we don't support py2.5 anymore)"
Revert "Use float.as_integer_ratio (we don't support py2.5 anymore)"

This reverts commit 95e0fb31f3de1ad38f8416a36e191bbd83390f8e.

This commit caused Rational to lose precision whenever it was passed a Float
with more than the default precision, since it was using Python's float to
get the integer ratio.

skidzo/sympy,jaimahajan1997/sympy,chaffra/sympy,madan96/sympy,kaushik94/sympy,yashsharan/sympy,madan96/sympy,skidzo/sympy,madan96/sympy,jaimahajan1997/sympy,skidzo/sympy,chaffra/sympy,jaimahajan1997/sympy,yashsharan/sympy,yashsharan/sympy,chaffra/sympy,kaushik94/sympy,kaushik94/sympy