Server autoupdate

This PR adds the necessary code for server autoupdating.

The client needs to put the data on the server by doing PUT /api/v1/version/new with something like
```
{
  'name': 'okpy',
  'file_data': 'abcddeadbeef',
  'version': '1.0.0'
}
```

Then do GET /api/v1/version?name=okpy, which will then give you the filedata and version.