APS Some process variable data types cannot be declared in the Activiti BPMN Editor

Summary
Currently while declaring process variables in the BPMN editor there is only the option to create variables of data type String, Integer, Boolean, People and Group. This should be extended to all other supported variable data types, e.g. float, decimal, date, datetime...

Steps to Reproduce

• In Activiti Kickstart create a process using the BPMN editor.
• In the process editor click on the variables section to create global process variables.
• Click on the plus sign to create a variable.

Actual Behavior
Only the following data types can be used: String, Integer, Boolean, People and Group (see also attached "dataTypes.png")

Expected Behavior
All variable data types supported by the engine should be able to be defined through the UI too, e.g. float, decimal, date, datetime.