Add depth estimation to the position of Overlay

[Waidhoferj]

Depth estimation should be normalized (between 0 and 1) so that the client can easily scale depth based on the size of the texture. This entails calling the findDepth API function with the correct Cloudinary image url, which can be found in the tour graph. When you get an array of depth values back, use the x and y position to index in to find the depth and set the z position of the overlay to that depth.