Support urls with/without trailing slashes in Nullstatic

[GuiDevloper]

Examples:
Accessing nullstack.app/contributors in Github Pages
Should work equal than accessing nullstack.app/contributors/

Targets those issues registered on Github Pages side:
jekyll/jekyll#4440
https://stackoverflow.com/questions/33270605/github-pages-trailing-slashes
https://marcgg.com/blog/2016/03/14/github-pages-jekyll/

[Mortaro]

This seems to be an issue with the way Github deals with trailing slashes.

I solved this by generating both versions of the file, for example: contributors.html and contributors/index.html

nullstack/create-nullstatic-app@eee4ea4

This solution should allow the programmer to not even think about structure while not having additional weight for the visitors.

By default Nullstack removes trailing slashes from router.path and rel canonical so this update should work greatly!