Creating bootable USB from "Install OS X El Capitan.iso"
All I did was wrote the image to USB Drive with dd command from the terminal and it booted like a charm. The command I used was:

$ diskutil list
$ cd /path/to/Install_OS_X_10.11_El_Capitan.iso
$ sudo dd if=Install_OS_X_10.11_El_Capitan.iso of=/dev/disk2 bs=1m


Replace disk2 with the appropriate drive listed in the output of the first command. For example, disk3 or disk4.