Update selected row to match Mountain Lion

[rtgibbons]

Small customization to the theme, I wasn't sure where to share this. The default texture for tree_row was a bit to bright for me

Before

After

Just added this to my user config for the theme

{
  "class": "tree_row",
  "layer0.texture": "Theme - Default/sidebar-row-selected.png",
}

Here is the texture https://dl.dropboxusercontent.com/u/1867918/sidebar-row-selected.png