[Applied]
Require Edm. in URL and CSDL, prohibit in Atom and JSON
Accepted: https://www.oasis-open.org/committees/download.php/49055/odata-meeting-35_on-20130502-minutes.html#odata-354
Currently the Edm. prefix is optional for built-in primitive types.
Referring to all types with qualified names is more consistent.