method: set_draggable -> need to use the secondary argument on set_class to true (append)

[mwd1993]

https://github.com/mwd1993/QuykHtml/blob/38505ba190119c97c18ac652997613f725dbb40b/QuykHtml.py#L1185

At the current momement, if a user specifies any classes and AFTER, calls the set_draggable method, it will overwrite the class data that the user specified.

needs to be changed to:

set_class('draggable', append=True)