cubicweb-relationwidget #10184485 Replace jqueryui pop-up by bootstrap [validation pending]

So that the look and feel is consistant with the other parts of the widget.

prioritynormal
typeenhancement
done in0.3.3
load0.500
load left0.000
closed by<not specified>
patchAdd a dedicated css class to the relation widget modal [applied]Change modal window library from jquery.ui to bootstrap [applied]