Version 2.7

This is mostly a maintenance release:

• Improved installer, including option to select product page template and parent page, doctrine fixes (thanks @lvanstrijland for this work from quite some time ago)
• Add email header and footer to new user email
• Enable multiple selection of files when selecting additional product
• New variants related config option (thanks @QuentindevePro)
• Set of product defaults when programatically creating products
• Translation and database call improvements

Please note that the install and upgrade functions have been heavily re-worked in this version. Please upgrade installs carefully with backups.