Add configs for `image/vnd.microsoft.icon`

By default the configurations from this repository ensure that
`.ico` files are served with the `image/x-icon`¹ media type,
compressed, and with far future expires headers. However, not
all users use all the configurations provided by this project,
or in some cases, the headers are overwritten from the level
"beneath" Apache (e.g.: from `php`).

Looking at the results from the HTTP Archive² from 15.10.2014:

  +----+--------------------+---------------------------------+
  |    | number of requests |        media type               |
  +----+--------------------+---------------------------------+
  | 1  |            7406888 | image/jpeg                      |
  |    |                ... |                             ... |
* | 10 |             342964 | image/x-icon                    |
  |    |                ... |                             ... |
* | 17 |              85390 | image/vnd.microsoft.icon        |
  |    |                ... |                             ... |
  +----+--------------------+---------------------------------+

it's not surprising to see that the IANA registered³
`image/vnd.mimetype.icon` media type is also used quite often.

Other incorrect/unofficial media types are also used, but their
usage is either wrong or low enough to not justify their addition.

  +----+--------------------+---------------------------------+
  |    | number of requests |        media type               |
  +----+--------------------+---------------------------------+
  | 1  |             342964 | image/x-icon                    |
  | 2  |              98936 | text/html                       |
  | 3  |              85390 | image/vnd.microsoft.icon        |
  |    |                ... |                             ... |
  | 9  |                652 | image/x-ico                     |
  | 10 |                446 | image/ico                       |
  |    |                ... |                             ... |
  | 15 |                102 | image/icon                      |
  |    |                ... |                             ... |
  | 17 |                 94 | image/xicon                     |
  | 18 |                 82 | application/x-icon              |
  |    |                ... |                             ... |
  +----+--------------------+---------------------------------+

Because of the things stated above, the changes from this
commit will ensure that Apache will serve anything labeled with
the `image/vnd.microsoft.icon` compressed and with far future
expires headers.

- - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - -

¹ https://github.com/h5bp/html5-boilerplate/commit/37b5fec090d00f38de64b591bcddcb205aadf8ee
  http://blogs.msdn.com/b/ieinternals/archive/2011/02/11/ie9-release-candidate-minor-changes-list.aspx

² https://www.igvita.com/2013/06/20/http-archive-bigquery-web-performance-answers/

  Query used for the first table:

    select count(requestid) as number_of_requests,
           mimetype as media_type
    from [httparchive:runs.2014_10_15_requests]
    group by media_type
    order by number_of_requests desc;

  Query used for the second table:

    select count(requestid) as number_of_requests,
           mimetype as media_type
    from [httparchive:runs.2014_10_15_requests]
    where (lower(mimetype) contains "ico") or
          (
             regexp_match(lower(url), r'\.ico$') or
             regexp_match(lower(url), r'.ico\?')
          )
    group by media_type
    order by number_of_requests desc;

³ http://www.iana.org/assignments/media-types/image/vnd.microsoft.icon