[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
fixes DS-2118, adds assetstore.dir to the testing dspace.cfg.more fileweaver overlay
Merge pull request #619 from hardyoyo/DS-2118

fixes DS-2118, adds assetstore.dir to the testing dspace.cfg.more
Merge pull request #365 from mwoodiupui/DS-1738

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