Specify animation duration on individual links

Adds support for data-menu-duration attribute

@@ -15,6 +15,7 @@
Add MENU_DURATION_ATTR variable

@@ -132,10 +133,18 @@
Check if MENU_DURATION_ATTR atrribute is set on link.
If so, set animationDuration to attribute value, else use _duration() function

Signed-off-by: David Benson <dmbenson1978@gmail.com>