Lato-server user directory snapshot implementation

Called with GET API/V1/files/ (no path given).
Return a json. An example:
{
  "files": [
    {
      "filepath": "file.txt",
      "md5": "d41d8cd98f00b204e9800998ecf8427e",
      "mtime": 1402563085.4901447
    },
    {
      "filepath": "subdir/file.jpg",
      "md5": "3df98f6c17f38c655df61469eb414e0d",
      "mtime": 1402479419.229178
    }
  ]
}
Merge branch 'master' of https://github.com/corso-python-prato/share-system-team2

Conflicts:
	server/server.py

(all 6 tests passed)