Access mode of VolumesRW incorrectly deserialized

Given an inspect containing this:

    "VolumesRW": {
      "/foo": true,
      "/bar": true,
      "/baz": false
    },

VolumesRW will not be deserialized correctly. The accessMode on the /baz volume will be set to rw instead of ro.

So, this logic doesn't work:

Line 107 in 8c948b1

return Volume.parse(field.getKey());

It needs to take the value into account, not just the key.