Add configs for bitmap image files (`.bmp`)

Ensure that `.bmp` files will:

 * be served compressed (BMP image formats¹ are either not natively
   compressed, or use RLE compression which achieves poor compression
   ratios, therefore, they compress quite nicely)
 * be served with far future expires headers
 * not be served with any of the `HTML` document related headers

Notes:

 * All Apache versions ≥ v2.2.0 will serve by default `.bmp` files with
   the `image/bmp` media type:
   https://github.com/apache/httpd/blob/2.2.0/docs/conf/mime.types#L452

 * While BMP images are not a suitable image format for the web, a
   decent number of sites still use them.

   e.g.: Looking into the HTTP Archive² at the results from 01.09.2014,
   4312 requests were made to BMP images, 4094 (~94.94%) of them being
   served uncompressed.

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

¹ https://en.wikipedia.org/wiki/BMP_file_format
² https://www.igvita.com/2013/06/20/http-archive-bigquery-web-performance-answers/