did a type check on next in default error handelers
made check for next a little smarter
Merge pull request #15 from MauriceButler/saftey-check

Type check for `next` function in default error handelers
405 handlers are now guarenteed to receive at most three parameters (req, res, and next if available).  Also added tests. #15
Removed redundant checks. #15
Bumped version number.