Add assets to gitattributes and gitignore

.gitattributes

@@ -0,0 +1,14 @@
+# Images
+*.bmp                binary
+*.exr                binary
+*.gif                binary
+*.hdr                binary
+*.iff                binary
+*.jpeg               binary
+*.jpg                binary
+*.pict               binary
+*.png                binary
+*.psd                binary
+*.tga                binary
+*.tif                binary
+*.tiff               binary