Made the upgrade window more user friendly.

I made it so that users can add and remove upgrades while on the upgrade screen, changes are saved when the user clicks the submit button and then the changes are locked.

Screenshot:
![image](https://cloud.githubusercontent.com/assets/1839179/3635623/04574354-0f81-11e4-9cce-aa5e068a061e.png)

Here are the submit images I used as well:
![submit_hover](https://cloud.githubusercontent.com/assets/1839179/3635627/12f9f14a-0f81-11e4-9ffc-0916fc6b40b9.jpg)
![submit](https://cloud.githubusercontent.com/assets/1839179/3635628/12faa374-0f81-11e4-8bb0-520f756b7e01.jpg)