Support for non-trailing slash

[NetOpWibby]

Currently, any route aside from the landing page that does not end in .html doesn't load if there is no trailing slash.

These may help:

• https://router.vuejs.org/guide/essentials/redirect-and-alias.html#redirect
• https://github.com/vuejs/vue-router/blob/dev/examples/route-alias/app.js

[NetOpWibby]

More references

• SEO friendly URLs vuejs/vuepress#78

• https://github.com/vuejs/vuepress/blob/0021fda45197f8d2575877b24b41c43c61a05aff/docs/guide/markdown.md#links

  When writing the relative path to a directory's index.html, don't forget to close it off with a /, otherwise you will get a 404. For example, use /config/ instead of /config.

Seems like this issue was "fixed" in Vuepress ages ago:

• vuejs/vuepress@99bc0aa

This issue has some overlap to #25. I've tried modifying server.js to utilize Express' redirect powers but that was a fruitless endeavor.

I've already spent too much time on this, it appears to be out of our hands as long as we're using Vuepress.