load the network stats earlier during the page load

[gruns]

after #185, the next optimization to load the network stats faster is to fire off the network request earlier during the page load

two techniques to accomplish this come to mind:

1. add a cache header to the response so its cached and then add a <link rel="preload" ... tag to fetch this content async immediately on page load
2. modify the js to make the request earlier

this isnt much work but is also very low priority. network stats load speed is, right now, currently in the 'acceptable' range

[patrickwoodhead]

It seems the network stats sometimes are not loading in time and so can fail and default to 100 nodes. This is not always the behaviour, but occurs if the request takes more than 10 seconds to resolve.