idea: add dynamic loader to gateway http frontend

[prusnak]

When I use gateway there is no indication for the user what is currently going on. I keep staring at the screen for several minutes, but have no idea whether the gateway is down, or it is still downloading the resource, or resource is not available or something else.

The idea is to add a dynamic loader, which gets sent to the browser first and would show progress and other useful info to the user. When the resource is finally available it would refresh the page and show the desired content.

This behavior would not be default, because this would obviously break a lot of stuff, but would be triggered when ?loader or similar is appended to the URL. That way one can set "dnslink=/ipns/Q0123456hash?loader" in their DNS TXT record and create a pleasant user experience for their users.

[whyrusleeping]

Interesting idea. Would need to figure out how it should actually work.

cc web people: @dignifiedquire @diasdavid @lgierth

I think this one would cover it: ipfs/go-ipfs-gateway#5