GuestAgent message validation

Change-Id: Ic96dedaa2d0cf68270be0d74eadee3108501c66a
Signed-off-by: Vinzenz Feenstra <vfeenstr@redhat.com>
String conversion

Change-Id: Ie277069cbfa39f9735a2b85b9e9da9c3fcfe5938
Signed-off-by: Vinzenz Feenstra <vfeenstr@redhat.com>
More encoding tests

Change-Id: I4c1d740c948e33aed8a04a1013b22276cf7d85e3
Signed-off-by: Vinzenz Feenstra <vfeenstr@redhat.com>