Update Zones to remain in alphabetical order

We had been doing this until recently, but "Firefox Marketplace" and
"Add-ons" ended up out of order.

Dropping "Persona" from the homepage feels strange, but we have the
following bug open for solving this long term.

https://bugzilla.mozilla.org/show_bug.cgi?id=946777
Rename StackOverflow on Learn JavaScript page

> Stack Overflow is a programmer Q&A site on the Stack Exchange Network.
> As a name, Stack Overflow, is always written "Stack Overflow" (two
> words, capital letters).

http://stackexchange.com/legal/trademark-guidance
Merge pull request #1730 from openjck/stack-space-overflow

Rename StackOverflow on Learn JavaScript page
Merge pull request #1728 from openjck/alphabetize-zones

Update Zones to remain in alphabetical order
Create more accurate accordion opening and 'current' styling
Merge pull request #1729 from darkwing/zone-subnav-current

Create more accurate accordion opening and 'current' styling