Fix issue with named queries, for now just use unnamed

[ashkan18]

[WIP] still need to update readme and chagelog

This is big change, here we've done following:

• Switched to graphql-client which will provide us #2 and also better error handling and also we can use responses with . notation so we can do something like response.data.invoices.first.fee_in_cents
• We added named queries in #13 which simplified how we create queries and later parse them, it seems Graphql::Client can't parse named queries and doesn't like the generated AST, since we are not really using the name of the query and currently we don't support query variables its safe to not support name and for now we can just do

  client.query do
  query do
  invoices(id: [1]) do
    id
    fee_in_cents
  end
  end
  end

Follow up

• We are fetching schema inefficiently, we can download and reuse it and have task for reloading it if needed
• I think we should rename Graphlient::Client.query method to Graphlient::Client.execute word query is little overloaded in this context.

[antonengelhardt]

@dblock @ashkan18 Quick question: is it possible to name queries? I saw the other PR (#13) introducing that behavior and this which (somewhat) removes it again.

Thanks

[dblock]

Reading the description of this PR it sounds like that answer is "no" @antonengelhardt