message: Increase gas limit for query tests
diff: use cosmwasm_std::{from_binary, from_slice, HandleResponse, HumanAddr, InitResponse, MessageInfo};
  use cosmwasm_vm::{
  testing::{
  - handle, init, mock_env, mock_info, mock_instance, query, MockApi, MockQuerier, MockStorage,
  + handle, init, mock_env, mock_info, mock_instance_with_gas_limit, query, MockApi,
  + MockQuerier, MockStorage,
  },
  Instance,
  };
  @@ -32,7 +33,8 @@ use queue::contract::{
  static WASM: &[u8] = include_bytes!("../target/wasm32-unknown-unknown/release/queue.wasm");
  fn create_contract() -> (Instance<MockApi, MockStorage, MockQuerier>, MessageInfo) {
  - let mut deps = mock_instance(WASM, &[]);
  + let gas_limit = 500_000_000; // enough for many executions within one instance
  + let mut deps = mock_instance_with_gas_limit(WASM, gas_limit);
  let creator = HumanAddr(String::from("creator"));
  let info = mock_info(creator.as_str(), &[]);
  let res: InitResponse = init(&mut deps, mock_env(), info.clone(), InitMsg {}).unwrap();
  