m8-upgrade: upgraded to the latest versions of everything
m8-upgrade: replace HttpBody.apply with Httpentity.apply
m8-upgrade: replaced ContentType.xxx with ContentTypes.xxx
Fixed test that was broken by the new way we create HttpEntity instances.

Spray will now always generate EmptyEntity for an empty String and we can;t trick our way around it so it now becomes a hard rule that you cannot store an empty String. Not that that ever made much sense in the first place of course