Handle various genesis format

[youngjoon-lee]

The explorer reads the genesis by Panacea REST API.
But, the genesis JSON format have been changed so many times by Cosmos.
So, the genesis that the explorer receives could be various according to the Panacea version at the moment when the genesis was exported.

Therefore, the explorer should be able to handle various genesis format:
86bb813#diff-98fd39b055fa88347f759d587d182bca728e7f10db3fd5f03722dab85157e4beR75

The possible formats that have been discovered are:

{
  "gentxs": null
}

{
  "gentxs": [...]
}

{
  "genutil": {
    "gentxs": null
  }
}

{
  "genutil": {
    "gentxs": [...]
  }
}

FYI, @cl9200