gold looks more like the yellow from the original badge

This contribution adds reference to the web page of the lesson in the Carpentries and makes it easier for visitors who want to contribute to get familiar with the good first issue badge.
This adds a list of current maintainers to the README.md.

Signed-off-by: Maxim Belkin <maxim.belkin@gmail.com>

See apple.com/macos

* replace page.root with 'base' variable that knows path level

* deal with case of trailing / in URL

* use link to figure out path for logos

* simplify path building for favicons

* baseurl isn't used in our template so it can removed
* use 'base' variable for path root instead of unecessary http request to
  site.url

* replace page.root with 'base' variable that knows path level

* deal with case of trailing / in URL

* use link to figure out path for logos

* simplify path building for favicons

* baseurl isn't used in our template so it can removed
* use 'base' variable for path root instead of unecessary http request to
  site.url

* rename variable, consolidate comments

* rename variable in template files

Pull Request carpentries/styles#330
Closes carpentries/styles#343

1. Fix the script so that all figures are displayed.
2. Add image numbers.
3. Don't add headers for episodes without images.
4. Add horizontal rulers to better separate adjacent images.
   Don't add a ruler after the last image in the episode.
5. Add empty lines to `figures.md` to improve code readability.
6. Use classes for styling text and figures

Close carpentries/styles#325

CODE_OF_CONDUCT.md is already at the root of the repository.

* Add 'cp' (Carpentry) as a lesson type (for instructor training)
* Explain lesson type abbreviations (swc, dc, lc, cp)
* Emphasize the fact that there is no need to edit "repository" variable in front matter

Closes swcarpentry/styles#283

`site.email` is used as:

_includes/lesson_footer.html:	        <a href="mailto:{{ site.email }}">Contact</a>
_includes/workshop_footer.html:	<a href="mailto:{{ site.email }}">Contact</a>

Therefore, it does not make sense to have `mailto` in the `email` itself.

See https://help.github.com/articles/about-community-profiles-for-public-repositories/.

Port of https://github.com/swcarpentry/r-novice-inflammation/commit/9da857efb16d7351127f2d5c46fc0af660654506.

Close swcarpentry/styles#274

This is a revamp of swcarpentry/styles#248.

Thanks to Andy Boughton.