Closes #31: Switch USB controller to USB3

Seems to solve USB related problems.

Author: ataffanel

bitcrazeVM_provisionVM.json

@@ -17,7 +17,7 @@
     "format": "ova",
 
     "vboxmanage": [
-      ["modifyvm", "{{.Name}}", "--memory", "1024", "--vram", "16", "--mouse", "usbtablet", "--rtcuseutc", "on", "--audio", "pulse", "--audiocodec", "ad1980", "--usb", "on", "--usbehci", "on", "--nestedpaging", "off"],
+      ["modifyvm", "{{.Name}}", "--memory", "1024", "--vram", "16", "--mouse", "usbtablet", "--rtcuseutc", "on", "--audio", "pulse", "--audiocodec", "ad1980", "--usb", "on", "--usbxhci", "on", "--nestedpaging", "off"],
       ["storageattach", "{{.Name}}", "--storagectl", "SATA Controller", "--port", "0", "--nonrotational", "on", "--discard", "on"]
     ],
     "import_opts": "importtovdi",