Formatting
Renamed allowed-request? to authenticate-request

This is because we are not yet determining whether the request is
allowed to proceed at this stage, so the name is misleading.
Rename allowed-user? with authenticate-user

This function is determining the user's existence and roles, rather than
whether the user is allowed to proceed with the request in context.
Break into separate namespaces

Cylon is a big system, it is easier to comprehend in pieces and using
namespaces can help reveal dependencies between the parts
Authorizations (unfinished)