previous code was exercising some changes on the uuid boost::mt19937_64 ...

...Uuids::ng_

object through the UuidsInitializer.
At issue was that the constructor of the Uuids::ng_ object was not called at the time
the seed was being set in Uuids::initialize_(). This surfaced in ng_ always having
its default initilization and always generating the same sequence of uuids through
the cass_uuid_generate_random call.

This fix will make sure the seed from the random_device is not overwritten