Remove the org package, closes #464

As discussed in #464. 

For anyone who reads this and happens to want to upgrade to this version of flixel, you can run a simple find and replace on your project source folder for this change.:
In FlashDevelop for example, right click on your source dir in the project panel and click on find and replace. Type "org." into the `Find what:` textfield and leave the `Replace with:` textfield empty. Also make sure to check the "Whole word" option! Then simply click `Replace` and you should be good to go!