Provide timeout as a config value

[roynalnaruto]

In the following function

@spec call(atom(), atom(), list()) :: {:ok, any()}
@doc "Use a Contract's method with an eth_call"
def call(contract_name, method_name, args \\ []) do
  GenServer.call(ContractManager, {:call, {contract_name, method_name, args}})
end

the GenServer request times out quite a few times while accessing data on the mainnet (because the default timeout is 5 seconds).

The timeout of Ethereumex.HttpClient can be set to :infinity, but the request times out at exw3.

Will it be helpful in allowing setting the GenServer timeout as a config value?

[hswick]

As long as the config param is optional it sounds okay to me.