Add Support for FreeBSD

[antonym]

Get FreeBSD working either with iPXE or with FreeBSD assets. The existing solution was using memdisk to load a raw hard disk image and broke Legacy when the cert used for mfsbsd no longer worked with https.

#302

We'd probably want this working with UEFI if possible too so we'd want to move away from the memdisk solution.

[thelamer]

You wanna keep this open trying to function with UEFI?

[antonym]

We can always revisit later, at least base functionality is working again but over the next few years I think Intel plans on dropping legacy support, so we should always try and favor UEFI when possible. Thanks for knocking this out!