[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
fixed an issue where running mvn package without clean would break the usemin step of the grunt build
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.
[DS-2034] Check for null (unset) properties and replace with an indicator
Merge pull request #622 from mwoodiupui/DS-2034

[DS-2034] Problem in [Control Panel]->[Dspace Configuration] - org.dspace.app.xmlui.wing.WingInvalidArgument: The 'characters' parameter is required for list items.
DS-2120: IdentifierServiceImpl should log less aggressive

The IdentifierProvider API uses exceptions to state that an Identifier
for a specific DSO cannot be found. These exceptions shoudln't get
logged as error.
Merge pull request #623 from tuub/DS-2120

DS-2120: IdentifierServiceImpl should log less aggressive
Merge pull request #618 from atmire/mirage2-usemin-issue

[DS-2116] Mirage 2 build fails without including maven clean target