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
Docs: Make minor grammar change in `extend.md`

Close h5bp/html5-boilerplate#1517.
Update to Normalize.css 3.0.1
Merge remote-tracking branch 'refs/remotes/html5-boilerplate.git/master'

Conflicts:
	css/normalize.css