Octane-ify Templates

[elwayman02]

Many of the route templates use a mish-mash of classic and Octane syntax. Some cleanup here would be nice, as well as enabling linting rules to enforce Octane patterns.

Example: https://github.com/empress/empress-blog-casper-template/blob/master/app/templates/post.hbs#L98

A few of the issues:

• {{link-to}} instead of <LinkTo>
• ambiguous paths due to implicit this usage
• {{svg-icons/infinity}} instead of <SvgIcons::Infinity>