Fix issue regarding quotes + CRLF line endings

On Windows, the following configuration:

  AddCharset utf-8 ".atom" \
                   ".css" \
                   ".geojson" \
                   ".js" \
                   ".json" \
                   ".jsonld" \
                   ".rss" \
                   ".topojson" \
                   ".vtt" \
                   ".webapp" \
                   ".xml"

namely the wrapping of the file extension strings in quotes in
combination with having CRLF line endings, somehow makes certain
Apache versions fail (e.g.: the Apache included with XAMPP).

This commit fixes the issue by removing the quotes¹.

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¹ The quotes were included mainly to ensure that Apache correctly
  interprets the strings, which, may not always happen, especially
  if the strings are more complex, see:
  https://github.com/h5bp/server-configs-apache/commit/4a3e5037531ae8d27f220484ce67c82cd4cf0752.

  Since file extensions usually contain only letters and numbers,
  the quotes can be omitted.

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Fix h5bp/server-configs-apache#35.