Description of problem:
If user morphs one kind of task to another, validation assumes that new kind of task contains also attributes of old kind of task.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Create new process
2. Add 'manual task' to canvas
3. Morph 'manual task' to 'script task' for example
4. Save process
There will be error, that 'script task' has no data type for 'Task Name' and 'Actor Id' which are not attributes of 'script task'
There will be not error, that 'script task' has no data type for 'Task Name' and 'Actor Id'