Parses provided XML, outputs data for XmlBuilder

Example

iex> xml = "<person id=\"12345\"><first>Josh</first><last>Nussbaum</last></person>"
...> data = XmlParser.parse xml
{:person, %{id: "12345"}, [{:first, nil, "Josh"}, {:last, nil, "Nussbaum"}]}
...> XmlBuilder.generate data
"<person id=\"12345\">\n\t<first>Josh</first>\n\t<last>Nussbaum</last>\n</person>"