VirtualBox WebService problems with '_this' element

Test spec to demonstrate problem with Savon when running against VirtualBox API.

[There is a further problem, I had to hack the import statement in the vboxwebService.wsdl file to include a specific file reference. Will deal with that issue separately, believe there is already a separate GitHub issue for this]

Signed-off-by: Ippoippo <ippoippo-software@ippoippo-eco.com>
First attempt at fix

We need to escape _ character.
So, example
'_this' means 'this' is an attribute of the parent element.
'__this' means '_this' is a child element of the parent element.

Signed-off-by: Ippoippo <ippoippo-software@ippoippo-eco.com>