Add support for writing image data output to a buffer, boosting ops/sec by ~7%. Partially implements #3.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "sharp",
-  "version": "0.0.6",
+  "version": "0.0.7",
   "author": "Lovell Fuller",
   "description": "High performance module to resize JPEG and PNG images using the libvips image processing library",
   "scripts": {
@@ -20,7 +20,8 @@
     "crop",
     "embed",
     "libvips",
-    "fast"
+    "fast",
+    "buffer"
   ],
   "devDependencies": {
     "imagemagick": "*",