Begin switching Articles section to Angular.js

Currently, only the index page and a non-functional Create page.

I will ensure all publicly viewable resources like the Index page and
article views work without JavaScript.
Add basic input error checking to article create
Add errors submodule to errors

errors.errors contains regular JavaScript errors. I need to move the
existing functions in errors to errors.handlers.
Refactor errors module

The errors module now has "errors" for Node.js Error objects, and
middleware for error handling middleware and middleware for less severe
problems.
Remove test code

There was some test code that generated and passed on an Error object
for every article API create request.
Fully implement article create form
Add cancel button to article create form
Implement article view

This now works on both the front end and the back end.
Move sluggify into article pre-save middleware
Move article slug create to pre-validate

It may not matter, but this lets us declare the slug as a required field
while still having it filled in automatically based on the title before saving.
Add basic article editing
Set path when fetching article for response

We set a `path` property on article objects with it's site path when we
load them with the fetchReqArticle function.
Add edit and delete paths when populating articles
Let fetchReqArticle check edit permissions

fetchReqArticle will check edit permissions and fetch the edit and
delete paths.
Add article delete form
Fix some syntax errors
Add IE and Android compatibility

The articles section now gracefully falls back to hash URLs when IE and
older Android browsers use it.

We also prevent IE from aggressively caching XMLHTTPRequest responses.
Fix redirect after article updates

The back-end wasn't updating the paths on the article object after it
was updated. The front-end ended up using the old path to redirect to
the article.
Redirect to new article after creation
Move ng-app property to html element

I also fixed the html tags in the conditional comments at the top. The
opening and closing html tags are inserted manually now.

The ng-app property is left out for IE8 and below. I don't need to
enable IE8 users to edit articles on this default site. All the Angular
app will do for IE8 users is make the URLs ugly, add strange delays
under some circumstances and break links within the page.

For business to business software, even IE8 users need to be able to log
in and edit. In that case, I will just have to put up with the
crustiness. If there are public-facing URLs that I really want to keep
clean, I can put them under a different prefix without an Angular app.