ensure suspected blossom request hash does not have slashes in it

[andrewheadricke]

I noticed certain URLs would be caught by the blossom url handler if they coincidentally split at 64 bytes. I am using a few extra path handlers.

This change adds a check for slashes. I was thinking a regex test might be better, but perhaps too resource heavy so just kept it as a Index call. Let me know if you prefer a regex test instead.