Upgrade GraphiQL to 0.4.9

This introduces the prettify button

Author: Josh Price

lib/graphql/plug/endpoint.ex

@@ -55,7 +55,7 @@ defmodule GraphQL.Plug.Endpoint do
  {:ok, data} = GraphQL.execute(schema, query, root_value, variables, operation_name)
  {:ok, variables} = Poison.encode(variables, pretty: true)
  {:ok, result} = Poison.encode(data, pretty: true)
- graphiql = graphiql_html("0.4.5", escape_newlines(query), escape_newlines(variables), escape_newlines(result))
+ graphiql = graphiql_html("0.4.9", escape_newlines(query), escape_newlines(variables), escape_newlines(result))
  conn
  |> put_resp_content_type("text/html")
  |> send_resp(200, graphiql)