Changed default stream frame rate adaptation mode, added suport of Pytorch 1.5.0

Changes

• Default NATIVE frame rate mode was changed.
  NATIVE frame rate mode brings time delay between RTMP stream and TensorStream result due to thread sleep work specific so this mode was replaced with new frame rate mode, which adapts for stream frame rate, based on stream metadata. Thus instead of synchronizing for fixed time, as it was done in previous implementation of NATIVE mode, synchronization by external data is used. Old implementation is available via NATIVE_SIMPLE mode.
• Added support for new Pytorch 1.5.0 version.