updating TODO.
added 'remove_namespaces!' class method for xml

- config gets a new 'remove_namespaces' accessor
- code works as it did before if remove_namespaces! is not present
Merge branch 'remove_namespaces' of https://github.com/canadaduane/representable into namespace
introduce Config#options.
some minor opinionated refactoring on remove_namespaces!.
extract XML#parse_xml.
releasing 1.7.1.