message: assign default runtime from config
diff: #include <appbase/application.hpp>
  #include <boost/program_options.hpp>
  #include <eosio/chain/wasm_interface.hpp>
  +#include <eosio/chain/config.hpp>
  namespace bpo = boost::program_options;
  using bpo::options_description;
  @@ -26,7 +27,7 @@ public:
  ~options();
  private:
  options();
  - vm_type wasm_runtime = wasm_interface::vm_type::wabt;
  + vm_type wasm_runtime = eosio::chain::config::default_wasm_runtime;
  variables_map & _options;
  };
  