Reverted header check back to original, so we handle one or both of 'If-None-Match' and 'If-Modified-Since' correctly.
Reverted header check back to original, so we handle one or both of 'If-None-Match' and 'If-Modified-Since' correctly.

janmonschke/node-static,cloudhead/node-static,hayksaakian/static_striationnutrition,lucasconstantino/node-static,winkapp/node-static,Slayer95/node-static,brodybits/node-static,hayashi311/node-static