Add pallet-assets (#94)

* init

* add assets to xcm transactor

* add empty genesis config for assets for now

node/src/chain_spec.rs

@@ -199,6 +199,7 @@ fn testnet_genesis(
         balances: parachain_template_runtime::BalancesConfig {
             balances: endowed_accounts.iter().cloned().map(|k| (k, 1 << 60)).collect(),
         },
+        assets: parachain_template_runtime::AssetsConfig::default(),
         parachain_info: parachain_template_runtime::ParachainInfoConfig {
             parachain_id: id,
             ..Default::default()