Updated CHANGELOG.md with entry about :host in asset_url

The name of the gem is `uglifier` and all other references
use `uglifier`, not `uglify`.

[ci skip]

sprockets-rails 2.1 needs the precompile list to be available in all
environments.

Explain how form_for :article is able to pull in the properties of @article
Make it clear that article_id is generated due to the association set up

Add link to the rails function that uses X-Sendfile.
Add links to apache and nginx docs for the header

By default `config.assets.raise_runtime_errors` should be set to `true` in development for new apps.

Source: https://github.com/rails/sprockets-rails/pull/100

[ci skip]

- Right now the comment was not rendering properly.
  # The Expires* directives requires the Apache module
  `mod_expires` to be
  # enabled.
- After this change -
  # The Expires* directives requires the Apache module
  # `mod_expires` to be enabled.

by default included to precompile only non-js/css files from `app/assets` and `application.(css|js)`

Replaced <br /> with <br> for consistency; Added note about
singular/plural distinction (which was previously confusing to a Rails
noob); Rephrased explanation of how form is routed to controller, again
to reduce confusion; and added explanation to replace incorrect link.
[ci skip]

specifically manifest.json

You need to specify `RAILS_ENV=production`

Related to https://github.com/rails/sass-rails/issues/152.

/cc @guilleiguaran

rake assets:precompile will work if config.assets.precompile is in config/application.rb and not in config/environment/production.rb

`if defined?(Bundler)` is no longer used in our current application.rb

Revert "added details to section 4.1.2 of the Asset Pipeline guide, describing how to configure Apache to serve the gzipped version of the precompiled assets"

This reverts commit aec466e7.

Reason: We're not sure about the correctness and won't want to document
something like this with doubts.

added details to section 4.1.2 of the Asset Pipeline guide, describing how to configure Apache to serve the gzipped version of the precompiled assets

to avoid unnecessary reg ex parsing and code
<http://httpd.apache.org/docs/2.2/mod/core.html#location
(recommended by @jja). - @erikj

* 1.9 hash syntax
* proper formatting around one line blocks
* do-end for multiline blocks