refactor/standardize remote proof workflow

[daviddahl]

It would be nice to create a standard class with standard methods to allow for easy adding of social proof published sites.

So, extract out the Gist code and reddit code and make a standard class that can be implemented for additional sources of proofs.

I imagine the interface implements something like:

• getRawData(url)
• extractProof(rawData)

Then the proof can just be handled generically

[cdeng001]

For building interfaces in js, are you ok with using duck typing?

the only other way to get C-like interfaces is to use a transpiler of some sort. typescript