pxe: Adding respawn as bash alias

Adding an alias will help people at calling respawn properly
pxe: Using lshw & fio for el7 release

Up to now we were using the el6 build of lshw on el7 which isn't that
clean.
server/upload*.py,build/init*: switch from a python file for hardware detection dict to a json one.
health: client have to send an hw structure, not a json

As the server expects the message to be an .hw structure, let's
transform the json to hw.