Flowable Task does not support Camel task

Hi all,

Using Flowable Modeler, I created an application containing a process definition containing Camel tasks. The process definition was deployed into the BPMN engine embbeded in Flowable Tasks. I get the following error. I think that it's due to the missing module `flowable-camel` in Flowable Task:
```
org.flowable.common.engine.api.FlowableException: Could not find org.flowable.camel.CamelBehavior:
at org.flowable.engine.impl.bpmn.parser.factory.DefaultActivityBehaviorFactory.createCamelActivityBehavior(DefaultActivityBehaviorFactory.java:287) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.factory.DefaultActivityBehaviorFactory.createCamelActivityBehavior(DefaultActivityBehaviorFactory.java:252) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.handler.ServiceTaskParseHandler.executeParse(ServiceTaskParseHandler.java:49) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.handler.ServiceTaskParseHandler.executeParse(ServiceTaskParseHandler.java:27) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.handler.AbstractBpmnParseHandler.parse(AbstractBpmnParseHandler.java:57) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.handler.AbstractActivityBpmnParseHandler.parse(AbstractActivityBpmnParseHandler.java:33) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.BpmnParseHandlers.parseElement(BpmnParseHandlers.java:79) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.BpmnParse.processFlowElements(BpmnParse.java:311) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.handler.ProcessParseHandler.transformProcess(ProcessParseHandler.java:76) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.handler.ProcessParseHandler.executeParse(ProcessParseHandler.java:49) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.handler.ProcessParseHandler.executeParse(ProcessParseHandler.java:33) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.handler.AbstractBpmnParseHandler.parse(AbstractBpmnParseHandler.java:57) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.BpmnParseHandlers.parseElement(BpmnParseHandlers.java:79) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.BpmnParse.applyParseHandlers(BpmnParse.java:282) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.parser.BpmnParse.execute(BpmnParse.java:195) ~[flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
at org.flowable.engine.impl.bpmn.deployer.ParsedDeploymentBuilder.createBpmnParseFromResource(ParsedDeploymentBuilder.java:97) [flowable-engine-6.4.0-SNAPSHOT.jar:6.4.0-SNAPSHOT]
...
```

So, please, add support of Camel task in Flowable Task.

Regards,
Christophe