message: Updated README to use GenericImageView trait
  Updated the README to use `GenericImageView` trait. I'm just trying the examples, and this took a bit to figure out. I'll submit more PR's as I find more issues. :)
diff: @@ -183,7 +183,7 @@ The image format is determined from the path's file extension.
  ```rust
  extern crate image;
  -use image::GenericImage;
  +use image::GenericImageView;
  fn main() {
  // Use the open function to load an image from a Path.
  