internet connection check

Added a list to configuration.py.
To ensure inet conn is down a list of urls is checked.
If all urls fail then network really is down - not a single site.

skip mirrorlist generation
useful if only task is to set branch or protocols

objectivity: to have github show the html documentation
renamed `docs` to `mkdocs`
renamed `site` to `docs` (reverted from commit 45473572)

objectivity: to have github show the html documentation
renamed `docs` to `mkdocs`
renamed `site` to `docs`

rebuild site

updated docs

accept comma and space as separator

fixed - import

mirrors.json is fetched directly from github