Add performance testing

[Sebastian-Roth]

Adding some of those tests to the FOS inits (e.g. as simple scripts for people to use manually or even add as iPXE menu item) might help people find out about bottle necks in their setups:

https://forums.fogproject.org/topic/10459/can-you-make-fog-imaging-go-fast
https://forums.fogproject.org/topic/15945/performace-testing-slow-fog-imaging
FOGProject/fogproject#526
https://forums.fogproject.org/topic/16640/slow-image-deployment-speeds-after-updating-bzimage-files
https://forums.fogproject.org/post/130472