Bump to version 0.9.0

Version 0.9.0 adds the gruvbox theme by @freeware-preacher.

Author: Tony Crisci

package.json

@@ -32,7 +32,7 @@
     "mocha": "^2.3.3",
     "which": "^1.2.0"
   },
-  "version": "0.8.0",
+  "version": "0.9.0",
   "description": "Make your i3wm config a little more stylish",
   "scripts": {
     "test": "cake test",