Assistant Simple mobs + Clown random names

Well, this adds an Assistant simple mob. Both a male and female version. Their appearance is with standard grey jumpsuits, black shoes, grey backpacks, ID's, and PDA's. They also have black hair. The male one has short black hair, the female one has floor-length black hair. They also have random first and last names from the names files.
![dvgztde](https://cloud.githubusercontent.com/assets/4686269/5592560/0bae7bde-91dd-11e4-84ef-915e1888b28c.png)

Also, I made it so the Clown simple mobs also uses random names from the clown names file.