Binding provider rethrow in DEBUG mode

When building a page we typically use Knockout in `DEBUG` mode. When there are parse binding failures, currently it throws an `Error` exception which removes the stack trace, which can make it fairly tricky to find where the binding failure occured.

This pull request disables this behavior in `DEBUG` mode and lets the exception propagate by rethrowing.

The original binding failure message is not shown (mainly because I wasn't sure how to do that cleanly since the rest of Knockout doesn't use `console` anywhere, for instance).