Body property holds full body that will be sent to the
client (but without headers!).
When Body property is accessed, wodWebServer will actually
open file defined in Filename
property, read/write to it and present it to you as String
value.
If Filename property isn't specified, when you
access Body property wodWebServer will create temporary
file and write to it. This file will be deleted when
Response is
sent to the client, and destroyed.