Fix spelling error

Thanks to Daniel Morais for pointing this out.
Rename, in the sidebar, Hints => Quick reference
Adjust HTML page title to say 'Quick reference'
Adjust text to be more like a quick reference
Add more-clear link to further, external resources about tar

Thanks to berryp for suggesting this.
Merge branch 'feature/issue639'
Adding description of power structure within OpenHatch

Closes: https://openhatch.org/bugs/issue532
Merge branch 'feature/document-leadership-etc'
Remove 3 of 5 files for recursive diff mission

This simplifies the mission -- now you only have
to edit two files, not five.

Closes: https://openhatch.org/bugs/issue619
Code cleanup (remove unused code and fix a comment)

"code" was to enable backwards compatibility for a file which is no longer part
of the training mission.
Merge branch 'feature/issue619'
Enable git serving over HTTP

This, combined with changes to Apache on linode.openhatch.org,
let people do git clones over HTTP. This is important because
sometimes people try to use the git training mission from
within restrictive firewalls.

Closes: http://openhatch.org/bugs/issue653
Merge branch 'feature/git-over-http'
Single diff mission: Slightly simpler exercise files
Add a commit verifying that if \n becomes \r\n it still works
Merge branch 'feature/simpler_second_diffpatch'
Move widget.html back into place

This fixes the account/widget view.

Closes: https://openhatch.org/bugs/issue724
Merge branch 'feature/issue724'
Permit multiple closed_status values by separating with commas

This is necessary for issue661, where Roundup-based bug trackers can have
multiple closed values (e.g., "resolved", "needs-review", "invalid")
Add test for comma-separated status

Closes: https://openhatch.org/bugs/issue661