5: Improve demos 

Task-Url:
https://github.com/unitsofmeasurement/unit-demos/issues/issue/5
5: Add SI module 

Task-Url: https://github.com/unitsofmeasurement/unit-lib/issues/issue/5
UNITSOFMEASUREMENT-13: Do we need AbstractMeasurement in RI? 

Task-Url: https://java.net/jira/browse/UNITSOFMEASUREMENT-13
32: Refactor some inconsistent naming 

Task-Url:
https://github.com/unitsofmeasurement/unit-impl-se/issues/issues/issue/32