Update channel.json - Added X3-Alpha Color Scheme

Added X3-Alpha Color Scheme to the list

![ss1](https://cloud.githubusercontent.com/assets/10118841/5427308/bfa61be4-836c-11e4-9955-da35a615d53e.png)
![ss2](https://cloud.githubusercontent.com/assets/10118841/5427309/bfa83a78-836c-11e4-9979-e2292b947867.png)
![ss3](https://cloud.githubusercontent.com/assets/10118841/5427310/bfabfd7a-836c-11e4-874a-48303a8df780.png)