Corona: Drop ErrorEnumTrait trait.

This has now been superceded by the HttpCode constants.
Corona: Remove json methods from the RequestInterface.

At this point they cause more confusion than they add value. With
data traffic being less of an issue these days, drop functionality
for confusing short keys for webservice input/output.
Spawn: Drop json related methods from the ResqueRequest class.
Shadow: Drop json related methods from the CliRequest class.
Corona: Drop json related methods from the Request class.
Corona: Drop the JsonEnumTrait trait.