[OLINGO-60] Deleted unnecessary EdmLiteral and moved EdmMapping

Moved EdmMapping since it is a helper and not mentioned inside the
specification.

EdmLiteral was a helper but is propably not needed in V4 anymore so I
deleted it.
[OLINGO-62] Bugfix for FunctionMapKey

Make sure the passed parameter list is sorted.
[OLINGO-66] First prototype with jackson library