text: Title: VOT19 json data format
  Body: Hi, when I try to run VOT2019 benchmark using pysot toolkit, I found that there might be some problems in VOT2019.json.
  The paths in json file are like "**img_names**": ["agility/00000001.jpg",...]
  but it should be "**img_names**": ["agility/color/00000001.jpg",...].
  