Fix issue 2096: 1/0 should be zoo, not oo
Fix failures in series module due to substitution of zoo as Order point
Fix test failures in concrete module.  XXX: why zoo.is_number is False?
Fix Integral.as_sum: use limits to handle boundaries, not subs
Fix Rational.__div__ to return zoo if other is S.Zero and self is not
Merge pull request #2813 from skirpichev/2096-zoo

Fix issue 2096: 1/0 should be zoo, not oo