In order to provide a docx templater engine in python, this code gets the xml of the document and join all the tags ({my_tag}) to ensure that every tag is located in the same xml node.

Main idea got from: http://virantha.com/2013/08/16/reading-and-writing-microsoft-word-docx-files-with-python/

TODO: Apply a tag engine like django, velocity or whatever to the xml