Avoid drops on side-nav opening files

packages/rocketchat-ui-sidenav/side-nav/sideNav.coffee

@@ -51,6 +51,9 @@ Template.sideNav.events
 	'scroll .rooms-list': ->
 		menu.updateUnreadBars()
 
+	'dropped .side-nav': (e) ->
+		e.preventDefault()
+
 Template.sideNav.onRendered ->
 	SideNav.init()
 	menu.init()