Gradle example to ingest BPMN2 diagram

[eouthwaite]

Create example project:

• include MarkLogicWorkflow
• ingest BPMN2 diagram

depends on #19

[eouthwaite]

see https://github.com/marklogic-community/ml-gradle/wiki/Writing-your-own-task#custom-tasks-that-talk-to-the-client-rest-api for ingest