per #277 link now downloads windows installer rather than directing user to windows installer repository

better formatting - <p> tags for survey links

Move survey links outside of agenda

When people edit the workshop agenda they often end up removing the links to the surveys and then need SWC staff to re-send them.  Links are now moved outside the agenda.

add reminder to email admin

index.html: Comment out setup/ link to make installation-tests opt-in

Fixes `startdate` and `enddate` comments

Add note about fields that shouldn't change.

Close 274.

Made `git clone` optional for instructions

An attempt to make it even more clear which entries in index.html should be quoted and which not.

Use YYYY-MM-DD instead of "YYYY-MM-DD", which offends `tools/check.py`

CUSTOMIZATION.md: Fix 'administraotrs' -> 'administrators' typo

This snuck in with 48c5eda1 (Updating note on customization,
2015-01-21, #138).

Sometimes instructors forget to customize their CHECKS, but learners
still follow this link and run the stock checks, resulting in a bunch
of confusing errors about missing packages that the learner doesn't
actually need [1,2,3,4].  Instead of expecting instructors to edit
CHECKS or remove the setup/ reference from index.html (a default that
is right for nobody), this commit comments that setup/ reference out
(a default that is right for folks who don't want
installation-checks).  Instructors who *do* want installation checks
now need to do two things (uncomment the setup/ reference and update
CHECKS), but with both steps listed in CUSTOMIZATION they are more
likely to get that right.

[1]: https://github.com/swcarpentry/workshop-template/issues/136
[2]: https://github.com/swcarpentry/workshop-template/issues/180
[3]: https://github.com/swcarpentry/workshop-template/issues/181
[4]: https://github.com/swcarpentry/workshop-template/issues/258

Added note on installing Jekyll with specific version of Ruby

This reverts commit 8d0905be.

Minor typo fix.

Link directly to Windows Installer repo for executable

To avoid the manual step of emailing and uploading new releases of the
Windows Installer this moves to downloading the file directly from the GitHub
release and updating the associated link in _config.yml.

index: Add HTML IDs to sections that lacked them

added survey to config.yml edit index.html links

Meta tags

"join" filter only works on lists (arrays), so when `instructor`
or `helper` are strings (or empty objects) then the result will be "".

But when they are arrays of strings, then the result will be like:
"Piotr Banaszkiewicz|Greg Wilson".

People can be named "John Smith, Jr.", but (probably) not
"John Smith| Jr."

I missed anchors for linking to the syllabus today.  The "syllabus-"
prefix avoids colliding with the existing setup IDs
(e.g. "syllabus-shell" for the syllabus entry and "shell" for the
setup entry).