Fixed #PRIS-58, #PRIS-59 and #PRIS-60

* Refactored the mapper and source implementations into seperated maven
    packages
* Refactored mapper and source identifiers to be more simple and
    speaking
* Moved from hard implementation registration to plugin interfaces
* Simplified mapper and source configuration names
* Changed docu accordingly
Fixed used slf4j adapter
Merge remote-tracking branch 'origin/develop' into feature-kaboom

Fixed #PRIS-71.

Conflicts:
	opennms-pris-main/src/main/java/org/opennms/pris/RequisitionGenerator.java
Fixed distribution to work with plugin infrastructure.

* Added a lib folder containing the implementations
* Added automatic creation and population of lib folder to distribution
    module
* Changed init script to add lib folder to classpath
Removed VMware plugin