Release 0.4.7.

1. Don't prevent the default scrolling for the inactive axis.
2. Enhance the scrolling logic.
3. Implement Home, End, Page Up, Page Down and Spacebar for the key
   scrolling.
4. Bug fixes.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "perfect-scrollbar",
-  "version": "0.4.6",
+  "version": "0.4.7",
   "engines": {
     "node": ">= 0.8.0"
   },