Change default Hierarchy Delimiter

[bupp925]

https://github.com/SearchSpring/magento2-searchspring-feed/blob/master/Helper/Generator.php#L76

Don't have this set to '/' by default; please update to use '>' as the default.

This is such a common-enough character that having '/' as the default runs the risk of overlooking setting the hierarchyDelimiter via the regen options, breaking some backgroundFilter or filter option along the way.