Add support to create background tasks in ios

[DurankGts]

Please check this thread in stack over flow.

https://stackoverflow.com/questions/57927881/how-to-fix-app-store-connect-operation-error-itms-90771

you must create a way to add a simple class in the codenameone side to execute a background task.

[DurankGts]

When my app goes to background all the Threads is stopped actually.