DDS15 — Add name attribute to Entity

Problem:
For system management it is very useful that Entities can be identified by a logical application defined name. This attribute should ideal be set via the factory create call but if changing API's is not desired it can also be set via a QoS policy. This attribute should also be supported by the built-in Topics

Solution:
Introduction of a new Properties QoS that can be used for a name, but also for other things. The new QoS would contain a sequence of "properties" where each property is a pair of strings:
(property_name, property_value)
This Properties QoS can be used very much the same as the USER_DATA, but because each property is named, multiple things can be stored without conflicting with each other. This also provides an extensibility mechanism for the DDS spec. We can reserve the property-names with the prefix "DDS." To indicate "built-in" properties that should not be used by applications.
We can use this mechanism with the built-in property name "DDS.EntityName" to implement the name attribute.