allows for nested dragging with handles sans disabling

[ajspera]

allows for nested dragging with handles without the need for disabling parent or child

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• Bug fix for nested handles

• Feature for nested dragging without the need for disabling

• What is the current behavior? (You can also link to an open issue here)

• Handles have not been working in a drop zone at all

• Nested draggables require disabling the parent to drag the child

  193 #58 #20 #56

• What is the new behavior (if this is a feature change)?

• Allows for handles within a drop zone

• Nested draggables do not require disabling the parent if the parent has a handle

• Other information:

[ajspera]

Sorry something's not testing right, presumably has to do with the timeout I needed to delay binding before checking for a handle was possible.