Add delay to dragging to support libraries that require the mouse be …

…held before dragging (#257)

lib/capybara/cuprite/browser.rb

@@ -139,23 +139,25 @@ def source
         raise NotImplementedError
       end
 
-      def drag(node, other, steps)
+      def drag(node, other, steps, delay = nil)
         x1, y1 = node.find_position
         x2, y2 = other.find_position
 
         mouse.move(x: x1, y: y1)
         mouse.down
+        sleep delay if delay
         mouse.move(x: x2, y: y2, steps: steps)
         mouse.up
       end
 
-      def drag_by(node, x, y, steps)
+      def drag_by(node, x, y, steps, delay = nil)
         x1, y1 = node.find_position
         x2 = x1 + x
         y2 = y1 + y
 
         mouse.move(x: x1, y: y1)
         mouse.down
+        sleep delay if delay
         mouse.move(x: x2, y: y2, steps: steps)
         mouse.up
       end

lib/capybara/cuprite/node.rb

@@ -162,13 +162,13 @@ def hover
       def drag_to(other, **options)
         options[:steps] ||= 1
 
-        command(:drag, other.node, options[:steps])
+        command(:drag, other.node, options[:steps], options[:delay])
       end
 
       def drag_by(x, y, **options)
         options[:steps] ||= 1
 
-        command(:drag_by, x, y, options[:steps])
+        command(:drag_by, x, y, options[:steps], options[:delay])
       end
 
       def trigger(event)