[RFT] Refactored MeterMeasure from inner class of DCS IP Driver to a normal class.

The DCS (Data Connectivity Service) IP Driver, was getting huge with no need.
Since there is a package for meter's based on ip, MeterMeasure doesn't need to be an inner class of the DCS IP Driver.
[RFT] Refactored the KNX Gateway Default Port to a final constant, instead of a literal.