jsonutils: do not require xmlrpclib

xmlrpclib isn't shipped anymore in Python 3, so let's support it
optionally.

Change-Id: Ic94f238a5f92f28ae1b6154fb56f00c4c9fa3283
jsonutils: make types py3 compatible

In Python 3, there's no long nor NoneType. Let's replace by equivalent
values.

Change-Id: Id1aa7af26b0f5d929337cc373c6a4f802bba2cec
Merge "jsonutils: do not require xmlrpclib"
Merge "jsonutils: make types py3 compatible"