add bluefin to boot_menu.yml

[akdev1l]

Problem

We need to allow people to easily setup their own boot_menu.yml (see #29) but this may take some effort. As an interim solution we should add Bluefin to the ISO as it is quite popular.

Solution

1. Added new option to release ISO that allows to install Bluefin to current boot_menu.yml

Acceptance Criteria

1. ISO boots and displays custom grub configuration showing Bluefin as an added option
2. ISO boot is otherwise unmodified

[akdev1l]

this was done