Ensure theme works with new `remote` GitHub Pages config option

[johno]

https://blog.github.com/2017-11-29-use-any-theme-with-github-pages/

[chfast]

I tried the remote_theme options and it does not seem to work.

[ashawley]

Supporting remote_theme is in progress, but it isn't ready, yet.

[kosperera]

I tried out @ashawley V3 with the remote_theme and it worked for me. Eagerly waiting for PR #396 to be merged to see it in action on my work.