Replace backslashes in th:replace in each HTML file

[Phrancis]

Backslashes in source HTML files that link using th:replace do not work correctly in an OS X environment. These need replaced by forward slashes to be compatible. We already tested it also works in non-OS X environments with forward slashes.

[Phrancis]

There are also other issues because of the very strict HTML5 syntax imposed by Thymeleaf. Since index.html is working perfectly, the easiest way to make other pages work as good will be to copy index.html code into other files, and add in the specific file content in the body of the other files.