[Feature][Q1'20] Ability to specify Encoder settings via config file

[wenquan-mao]

Requirements of feature:

1. During make start_kubernets Customer has ability to use default config file or specify custom config file for transcoding
   • Configuration file is used to configure encode/transcode session
2. Should be supported for both VOD and Transcode sessions
3. Config file to support arbitrary number of outputs per Input stream
4. Configuration file to support configuration of, but not limited to, following Encoder configurations
   • Codec
   • Preset
   • Output resolution
   • GOP Size
   • GOP configuration(LD/RA/B Pyramid etc…)
   • Bitrate rate controls
   • HRD configuration
   • Extra field where string is concatenated at end of encoder command so additional options can be passed to encoder

[wenquan-mao]

done