Fix for enhancements NMS-5962 and NMS-5963
Refactoring some code pieces to use JaxbUtils

The following classes were updated in order to use JaxbUtils instead of
managing and handling the JAXBContext directly.

- AccessPointMonitorConfigFactory
- AccessPointMonitorConfigTest
- JdbcDataCollectionConfigFactory
- JdbcDataCollectionConfigTest
- NCSNorthbounder
Fixing the JSON parsing in AbstractJsonCollectionHandler
Adding a CSS Selector based handler for the XML Collector.

Added JUnit test to verify:
- HTML processing with XPath with pre-parse-html (for malformed HTML)
- HTML processing with CSS Selectors (instead of XPath)
- JSON processing
Merge branch '1.12'

Conflicts:
	features/access-point-monitor/src/main/java/org/opennms/netmgt/config/accesspointmonitor/AccessPointMonitorConfigFactory.java
	features/jdbc-collector/src/main/java/org/opennms/netmgt/config/jdbc/JdbcDataCollectionConfigFactory.java
	features/ncs/ncs-northbounder/src/main/java/org/opennms/netmgt/ncs/northbounder/NCSNorthbounder.java
	protocols/xml/pom.xml
	protocols/xml/src/main/java/org/opennms/protocols/xml/collector/AbstractXmlCollectionHandler.java