Revert "took out preventDefault(); from skrollr"

This reverts commit 08b3b7839f784a2a72d12d40cedf7a2c16d6aa89.
Revert "Revert "took out preventDefault(); from skrollr""

This reverts commit 64b85e144e78c4f7e8e7624b5fa028c3aaf5fd39.