Redirect legacy traffic to legacy.polyfill.io in preparation for moving the service to the polyfill.io domain.
Revert "Redirect legacy traffic to legacy.polyfill.io in preparation for moving the service to the polyfill.io domain."

This reverts commit d44d1dc3a53ec4c839e13934809c9bc4eefb56a8.
Perform legacy redirect at Fastly.
Merge pull request #171 from Financial-Times/legacy-redirect

Redirect legacy traffic to legacy.polyfill.io