allow non-String default params in the router.

Closes #9435.

Skip valid encoding checks for non-String parameters that come
from the matched route's defaults.
Merge pull request #9439 from senny/9435_router_params_as_integers

convert non-string default params to strings in the router.
remove private attribute? warning
Merge pull request #9452 from frodsan/remove_private_attribute_warning

remove private attribute? warning