…for branding

Otherwise, some times are read as strings instead of ints,
because YAML gets confused about fields with colons that start with 0's,
as in '09:00:00' (no, really).

Otherwise, some times are read as strings instead of ints,
because YAML gets confused about fields with colons that start with 0's,
as in '09:00:00' (no, really).

Convert maps to lists so PyYAML works.

Python3 doesn't have unicode function.

    python3 ./bin/preprocess.py -c ./config -o /home/raniere/software-carpentry/site/_site -s /home/raniere/software-carpentry/site/_site
    Traceback (most recent call last):
      File "./bin/preprocess.py", line 253, in <module>
        main()
      File "./bin/preprocess.py", line 114, in main
        decorated.sort()
    TypeError: unorderable types: dict() < dict()
    Makefile:213: recipe for target '_config.yml' failed

Simply add retrieval of badges.yml, airports.yml before they're used in
generating `_config.yml` by `preprocess.py`.

List of airports is now closer to the list of badges (ie. people are
2-field objects:

{name: 'Piotr Banaszkiewicz', user: 'banaszkiewicz.piotr'})

And the list of instructors is called `instructors`, not `who`.

List of badges is not a dictionary anymore, so additional lookup is
required (via loop and if).
Also, people are in a field called `persons`, not in the unnamed list.

This is quite a big commit, but the basic changes are here:
1. No archive for workshops (since they're accessible via AMY API) -
   that'll change soon, ie. we'll add a 'make archive' option
2. Fixed duplicate command in Makefile
3. All workshops are marked either published or unpublished by
   `preprocess.py` because AMY returns all workshops considered
   published by its own criteria (less strict).
4. config/airports.yml, config/badges.yml and config/workshops.yml
   aren't needed anymore, since that data comes from AMY
5. Some fields changed names (ie. `startdate` became `start`, `enddate`
   became `end`).  That was quite straightforward to fix.

…for branding