Support of libfdk_aac audio codec

Added support of libfdk_aac audio codec.

<?xml version="1.0"?>
<query>
    <userid><<id>></userid> <!-- required-->
    <userkey><<key>></userkey> <!-- required-->
    <action>addMedia</action> <!-- required-->
    <source>[SourceFile]</source> <!-- required-->
    <format> <!-- required -->
        <output>[output]</output> <!-- required -->
        <audio_codec>[AudioCodec]</audio_codec>
        <!-- format params -->
    </format>
</query>

{
    "query": {
        "userid": "<<id>>", // required
        "userkey": "<<key>>", // required
        "action": "[Action]", // required
        "source": "[SourceFile]", // required
        "format": {
            "output": "[output]", // required
            // format params
        }
    }
}

Parameter	Description	Allowed Values	Default Value
audio_codec	Specify the audio codec	mp3: libmp3lame m4a: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2, eac3, eac3joc flv: libmp3lame, libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2 mp4: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2, ac3, eac3, eac3joc fl9, m4v, ipod, iphone, ipad: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2 wowza, roku_, kindle_fire: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2, eac3, eac3joc mov: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2, eac3, eac3joc, pcm_f32be, pcm_f32le iphone_stream, ipad_stream: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2 wowza_multibitrate, hds: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2, eac3, eac3joc smooth_streaming: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2, eac3, eac3joc advanced_hls, fmp4_hls, advanced_dash, advanced_fmp4: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2, ac3, eac3, eac3joc fmp4_hls, advanced_dash, advanced_fmp4: libfaac, dolby_aac, libfdk_aac, dolby_heaac, dolby_heaacv2, ac3, eac3, eac3joc wmv, wma, zune: wmav2, libmp3lame wav: pcm_s16le, pcm_s24le, pcm_s32le ogg, webm: libvorbis android: libamr_nb, libfaac, libfdk_aac mpeg2: pcm_s16be, pcm_s16le, ac3 mpeg1: mp2, copy mpegts: ac3, eac3, eac3joc, libfaac, libfdk_aac, libmp3lame, mp2, dolby_aac, dolby_heaac, dolby_heaacv2, copy mpeg_dash: libfaac, libfdk_aac, eac3, eac3joc mxf: pcm_s16le, pcm_s24le, copy dnxhd_mxf: pcm_s16le, pcm_s24le, copy apple_prores: pcm_s16le, pcm_s24le, pcm_s32le, libfaac, libfdk_aac cablelabs_mpegts: ac3, s302m, mp2 mainconcept_mxf*: pcm_s16le, pcm_s24le, copy	flv, mp3: libmp3lame fl9, mp4, m4v, ipod, iphone, ipad, wowza, kindle_fire: libfaac mov: libfaac iphone_stream, ipad_stream, wowza_multibitrate, smooth_streaming, hds: libfaac advanced_hls, fmp4_hls, advanced_dash, advanced_fmp4: libfaac wmv, zune: wmav2 wav: pcm_s16le ogg, webm: libvorbis android: libamr_nb mpeg2: pcm_s16be mpeg1: mp2 m4a: libfaac mpeg_dash: libfaac mpegts: ac3 mxf: pcm_s24le dnxhd_mxf: pcm_s16le apple_prores: pcm_s24le mainconcept_mxf: pcm_s24le