Added test in spiderfySpec for class add/remove
Added test in spiderfySpec for class add/remove

class "leaflet-cluster-anim" checks for add then remove when spiderfying / unspiderfying, and not left behing when removing MCG from map while it is spiderfied.

ghybs/Leaflet.markercluster,frenomus/Leaflet.markercluster,frenomus/Leaflet.markercluster,Leaflet/Leaflet.markercluster,ghybs/Leaflet.markercluster,Leaflet/Leaflet.markercluster