remove animation and switch to good ol' manly jQuery append

@hschink It might not be an issue in this code, I just removed it from the callback for the sake of consistency. The main reason for disabling animation was to combat flickering, and the workarounds for that where to set the visibility on and off or to move the element from the viewport before the animation starts. After it beings, it starts to invoke requestAnimationFrame and other cool stuff that displays the menu in the old position  for a small (but noticeable) fraction of time. I would gladly set the position before the animation starts, but I need the width and height of menu, and I can only get them once the menu is visible. It's some chicken and egg issue (or I am thinking in the wrong direction).