[DS-1738] Support NUMERIC columns in database query result sets.

NUMERIC and DECIMAL results are now converted to BigDecimal, not
Integer resp. Long.
[DS-1738] Reflect changes in MockDatabaseManager too.  Provide unit tests.
Proper license header for new test module
Code cleanup
Merge pull request #365 from mwoodiupui/DS-1738

[DS-1738] Support NUMERIC columns in database query result sets.