Support internationalization / multiple languages

[jdillard]

More information on multilingual sitemaps can be found here: https://en.wikipedia.org/wiki/Sitemaps#Multilingual_and_multinational_Sitemaps

Setting the language flag in conf.py: http://www.sphinx-doc.org/en/master/usage/configuration.html#confval-language

Setting the location of the locales in conf.py: http://www.sphinx-doc.org/en/master/usage/configuration.html#confval-locale_dirs

Building multiple languages: http://www.sphinx-doc.org/en/master/intl.html

Note: All the sitemaps will need to be manually added to a sitemapindex.