Add syntax highlighting for Embedded code

Add syntax highlighting for php, js, css embedded

before:
![1](https://f.cloud.github.com/assets/1000317/1843657/5d445e9e-74da-11e3-9177-f083fd360c57.png)

after:
![2](https://f.cloud.github.com/assets/1000317/1843658/623f534a-74da-11e3-933d-e3195c30d48c.png)