Further optimize `tile` images

 * tile.png

     before:        13767 B
     after:         13743 B
     ──────────────────────
     reduction:        24 B [0.17%]

 * tile-wide.png

     before:         6781 B
     after:          6774 B
     ──────────────────────
     reduction:         7 B [0.10%]
Update to Modernizr v2.8.0
Add `newline` at the end of the gitattributes file

Under UNIX-like OSes, a text file consists of a series of lines, each
of which ends with a `newline` character (`\n`). A file that is not
empty and does not end with a `newline` is therefore considered not to
be a text file.

Because of this, utilities that are supposed to operate on text files
may not cope well with files that don't end with a `newline` (e.g.: they
might ignore the text after the last `newline`).

Adding the `newline` character at the end of the file ensures that users
won't encounter any odd behavior when using it.

Reference/Source: http://unix.stackexchange.com/a/18789.
Update print related comments in `main.css` file

Use correct terminology and remove the outdated parts of the comments.

See also:

 * JavaScript URIs:
   https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/void#JavaScript_URIs

 * URL fragments:
   http://www.whatwg.org/specs/web-apps/current-work/multipage/history.html#scroll-to-fragid

 * `href` attribute:
   http://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#attr-link-href
   https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#attr-href
Fix file system permissions for `normalize.css`

Close #1537.
Remove empty line from `main.js`

Close h5bp/html5-boilerplate#1538.
Update `CONTRIBUTING.md`

* Remove extra `the`.
* Remove IRC reference as it does not help the user in
  any way, plus, we don't have an official IRC channel.