[4.2] Fix bug with array filters and using before/after method on route.

This fixes a bug where if you define either an array of filters on a route group or have multiple groups with multiple string based filters and then try to use either the `before` or `after` method on a route you'll get an "Array to string conversion" error.

Have added a test as well.

Signed-off-by: Jason Lewis <jason.lewis1991@gmail.com>