Update boxes to 64 bit

[denniswa]

From what I could see all the boxes are 32bit versions and those wont boot on VirtualBox 6 since 32bit hosts has been discontinued in 6.0.

I hope that the boxes will be updated to 64bit, I was under the impression that most Juniper devices are in fact running 64 bit now a days anyway... or at least that the documentation wrt installation will mention that you need to run older 5.2 version of VB.
Thanks!

[ctopher78]

I created #30 to update the docs until a 64bit box has been created.