Support ``git@github.com:foo/bar.git`` style repository url.

[h13i32maru]

Now, supports following url in package.json

{
    "repository": {
    "type": "git",
    "url": "https://github.com/foo/bar"
  }
}

But, does not support following url in package.json

  "repository": {
    "type": "git",
    "url": "git@github.com:foo/bar.git",
  }

[hideyuki]

🍺