Copy/install only selected bootstrap/bootswatch version and style/theme variant

[jenisys]

It would be better and more efficient if only the selected bootstrap/bootswatch version and the selected bootswatch variant would be installed/copied into the sphinx generated HTML directory tree.

This may require some "path-normalization" for page resources (CSS, JS, etc.) in the template and some logic that prevents sphinx from copying the whole theme.

In addition, it seems that only the "*.min.css" versions are really used by HTML page. If this is true, only these needed resources should be copied.