Add a facade for all Github HTTP interactions

[nateberkopec]

Githubbub stuff kind of litters the codebase r/n. There should be a Remote Facade.

[nateberkopec]

I.e. the only place we should be rescuing from Githubbub::RequestError is in the facade object. One has already been started in GithubFetcher, but it needs to be fleshed out.

As an example, here's what populate_docs! would look like with a proper remote facade:

def fetcher
  @fetcher ||= GithubFetcher.new(full_name)
end

def populate_docs!
    return unless can_doctor_docs?
    
    self.update!(commit_sha: fetcher.commit_sha) # Should never raise Githubbub::RequestError
    parser  = Repo::CLASS_FOR_DOC_LANGUAGE[self.language].new(fetcher.clone) # ditto, but deal with the nil case here too
    parser.process
    parser.store(self)
  end

[nateberkopec]

I.e. the only place we should be rescuing from Githubbub::RequestError is in the facade object. One has already been started in GithubFetcher, but it needs to be fleshed out.

As an example, here's what populate_docs! would look like with a proper remote facade:

def fetcher
  @fetcher ||= GithubFetcher.new(full_name)
end

def populate_docs!
    return unless can_doctor_docs?
    
    self.update!(commit_sha: fetcher.commit_sha) # Should never raise Githubbub::RequestError
    parser  = Repo::CLASS_FOR_DOC_LANGUAGE[self.language].new(fetcher.clone) # ditto, but deal with the nil case here too
    parser.process
    parser.store(self)
  end