Commit's short info model

Github api returns commit info in this way:
{
    "sha": "c77360d6f2ff2c2e6dd11828ad5dccf72419fa1b",
    "commit": {
      "author": {
        "name": "Kohsuke Kawaguchi",
        "email": "kk@kohsuke.org",
        "date": "2012-04-11T16:23:37Z"
      },
      "committer": {
        "name": "Kohsuke Kawaguchi",
        "email": "kk@kohsuke.org",
        "date": "2012-04-11T16:23:37Z"
      },
      "message": "Added a file",
      "tree": {
        "sha": "496d6428b9cf92981dc9495211e6e1120fb6f2ba",
        "url": "https://api.github.com/repos/kohsuke/test/git/trees/496d6428b9cf92981dc9495211e6e1120fb6f2ba"
      },
      "url": "https://api.github.com/repos/kohsuke/test/git/commits/c77360d6f2ff2c2e6dd11828ad5dccf72419fa1b",
      "comment_count": 0
    }, ...

github-api updated wuth necessary models in order to wrap new info