Fix Incorrect vboxmanage sudo command

Fix #247

gns3server/modules/virtualbox/__init__.py

@@ -97,7 +97,7 @@ class VirtualBox(BaseManager):
                 vbox_user = self.config.get_section_config("VirtualBox").get("vbox_user")
                 if vbox_user:
                     # TODO: test & review this part
-                    sudo_command = "sudo -i -u {}".format(vbox_user) + " ".join(command)
+                    sudo_command = "sudo -i -u {} ".format(vbox_user) + " ".join(command)
                     process = yield from asyncio.create_subprocess_shell(sudo_command, stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE)
                 else:
                     process = yield from asyncio.create_subprocess_exec(*command, stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE)