Support for default domains other than 0

[gmartin82]

trafficstars

At present the Cyclone DDS Python binding defaults to using 0 as the default domain when creating domain participants. Further, no option is present in the binding to allow users to automatically create domain participants on the default domain as determined by the core Cyclone DDS implementation and the configuration files.

It would be useful for the Python binding to provide a mechanism which allows users to create domain participants on the default domain as determined by the Cyclone DDS XML configuration file specified through the CYCLONEDDS_URI environment variable.