Docs: Update the `Apple Touch Icons` section

* Add note about `precomposed` not being required anymore, as starting
  with iOS 7, no special effects are applied to the touch icons.

* Add missing touch icon sizes.

Close #1488
Combine the `html` selectors into one rule

Close #1492.
Add `Disallow:` to `robots.txt`

The addition of `Disallow:` is made in order to be compliant with:

  * the `robots.txt` specification (http://www.robotstxt.org/), which
    specifies that: "At least one Disallow field needs to be present
    in a record"
  * what is suggested in the documentation of most of the major search
    engines, e.g.:

      - Baidu:  http://www.baidu.com/search/robots_english.html
      - Google: https://developers.google.com/webmasters/control-crawl-index/docs/getting_started
                http://www.youtube.com/watch?v=P7GY1fE5JQQ
      - Yandex: help.yandex.com/webmaster/controlling-robot/robots-txt.xml

Besides the addition specified above, this commit also:

  * adds a comment making it clear to everyone that the directives from
    the `robots.txt` file allow all content on the site to be crawled
  * updates the URL to `www.robotstxt.org`, as `robotstxt.org` doesn't
    quite work:

      curl -LsS robotstxt.org
      curl: (7) Failed connect to robotstxt.org:80; Operation timed out

Close #1487.
Merge remote-tracking branch 'upstream/master'
Further optimize `apple-touch-icon-precomposed`

  before:         1226 B
  after:          1076 B
  ──────────────────────
  reduction:      -150 B [-12.23%]
Update to Normalize.css 3.0.0
Update `CHANGELOG.md`
Update to jQuery 1.11.0

Close #1499.
Docs: Add `Separate mobile URLs` subsection

Inform users that, if they use separate URLs for desktop and mobile
users, they should consider helping search engine algorithms better
understand the configuration on their web site.

See also:

 * https://developers.google.com/webmasters/smartphone-sites/details#separateurls
 * https://developers.google.com/webmasters/smartphone-sites/feature-phones

Close #1504.
Make consistency changes

Change code indentation in `normalize.css` from 2 to 4 spaces. This
is done in order to be consistent with the indentation used in the
other files.
Update to Apache Server Configs 2.2.0
Add `/browserconfig.xml` and tile images

By default, starting with IE11 on Windows 8.1, IE will request the
`/browserconfig.xml` file when a user clicks/touches the `pin site`
button (same as Safari for iOS does with the `apple-touch-icons` when
the user touches the `share` button).

Adding the `/browserconfig.xml` file and the tile images:

* reduces the number of 404s, especially as IE11 on Windows 8.1 gets
  more market share
* provides a starting point for dealing with Windows tiles
* reminds users about the tile images, so that their website doesn't
  end up having as a tile the default IE11 logo, or (if the favicon
  is 32×32px or bigger and not `.ico`) the website's favicon
* unlike using `<meta>` tags, offers a way that doesn't increase the
  page size

Only two images are provided since:

* `tile.png` (558×558px) - can be used for the `Small`, `Medium`,
  and `Large` tiles, being automatically resized where necessary
* `tile-wide.png` (558×270px) - can be used for the `Wide` tile
  as, in this case, resizing the 558×558px image would just end up
  looking weird

The two images are 558×558px and 558×270px because those are the
recommended image sizes in order for the tiles to look good on a wide
range of devices.

For more in depth information, please refer to the MSDN documentation:

 * http://msdn.microsoft.com/en-us/library/ie/dn455106.aspx
 * http://msdn.microsoft.com/en-us/library/ie/dn255024.aspx

Close #1481.
Docs: Use Bootstrap instead of "Twitter Bootstrap"

"Twitter Bootstrap" is now simply known as "Bootstrap".

Ref: http://getbootstrap.com/about/#brand

Thanks @cvrebert.
Docs: Fix typo in `extend.md`

Close #1510.
Docs: Improve content about use of CDN for jQuery

Ref: https://github.com/h5bp/html5-boilerplate/issues/1498#issuecomment-33163993.
Close: #1511, #1514.
Update `CHANGELOG.md`

Include missing reference.
Docs: Update content regarding `Google Analytics`

Close: h5bp/html5-boilerplate#1490
       h5bp/html5-boilerplate#1515
Merge remote-tracking branch 'upstream/master'
Docs: Make minor grammar change in `extend.md`

Close h5bp/html5-boilerplate#1517.
Merge remote-tracking branch 'upstream/master'