Updating the python code in the C2 IP Range idiom so it generates valid XML.
Updated docs to reflect changes from this commit, STIXProject/python-stix@7f549a20ed7a596b9f1c510abfe5800fd4291c0b
Merge pull request #2 from mgoldsborough/optional_vocab_type

Updating the python code in the C2 IP Range idiom so it generates valid XML.