message: change default genesis timestamp
diff: namespace eosio { namespace chain {
  genesis_state::genesis_state() {
  - initial_timestamp = fc::time_point::from_iso_string( "2018-03-02T12:00:00" );
  + initial_timestamp = fc::time_point::from_iso_string( "2018-06-01T12:00:00" );
  initial_key = fc::variant(eosio_root_key).as<public_key_type>();
  }
  