Compare Two Commits does not include files array

[shiftkey]

This was implemented in #428 but the files element was overlooked.

files is an array of elements which looks like this:

  "files": [
    {
      "sha": "bbcd538c8e72b8c175046e27cc8f907076331401",
      "filename": "file1.txt",
      "status": "added",
      "additions": 103,
      "deletions": 21,
      "changes": 124,
      "blob_url": "https://github.com/octocat/Hello-World/blob/6dcb09b5b57875f334f61aebed695e2e4193db5e/file1.txt",
      "raw_url": "https://github.com/octocat/Hello-World/raw/6dcb09b5b57875f334f61aebed695e2e4193db5e/file1.txt",
      "contents_url": "https://api.github.com/repos/octocat/Hello-World/contents/file1.txt?ref=6dcb09b5b57875f334f61aebed695e2e4193db5e",
      "patch": "@@ -132,7 +132,7 @@ module Test @@ -1000,7 +1000,7 @@ module Test"
    }
  ]

[shiftkey]

Fixed in #608 and shipped in v0.6.0