Version 4

• phpunit tests removed in favour of phpSpecs
• Removed unused files
• Add composer.lock
• Add XML validation attributes to UrlSet and SitemapIndex
• Updated .gitattributes to remove more files from an export
• Use PSR-4 over PSR-0
• Updated namespace to Thepixeldeveloper\Sitemap
• Add support for Google Image sitemaps

Version 3

I've not been tagging releases when I should have been. This should fix up any issues bought up in #4