Subject: res_http_media_cache

When fetching a file for playback from a URL, Asterisk will now first
use the value of the Content-Type header in the HTTP response to
determine the format of the audio data, and only if it is unable to do
that will it attempt to parse the URL and extract the extension from
the path portion. Previously Asterisk would first look at the end of
the URL, which may have included query string parameters or a URL
fragment, which was error prone.
