[libSerialization] Support serialization of class with non-empty constructors

[renaudll]

The following class won't work with libSerialization.

from omtk.vendor import libSerialization

class Test(object):
    def __init__(self, arg):
        self.arg = arg

t = Test()
net = libSerialization.export_network(t)
libSerialization.import_network(net)  # fail

This will produce this error:

# Error: TypeError: file <maya console> line 7: __init__() takes exactly 2 arguments (1 given) #