Fixes issues with the header and footer 

Previously Monolith was not using the native Wordpress functions get_header() and get_footer(), and used get_template_parts() to call in the header and footer instead.

A new header.php and footer.php have been created and the old parts have been removed.  

This resolves an issue with Woocommerce not working correctly with some payment integrations (eg. Sagepay) and probably other unknown issues.