This adds id logging + validation to the Modeler. As a result the
modeler will throw hard exeptions on colliding id mappings and may
generated unique ids.
Related to bpmn-io/bpmn-js#92
Behind the scenes changes:
* use diagram-js Matcher util in tests
* add test cases for LayoutConnection
* add test cases for CreateConnection
* cleanup unused test diagram
Related to #2
This commit adds
* handling of bpmn update as command listeners
* label support
Related to bpmn-io/diagram-js#45
BREAKING CHANGE:
* rename bpmnModeling -> modeling to achive parity with diagram-js