Set approximate wallet fee to avoid LowFeeTransaction (#163)

Set approximate wallet fee when building a transaction so we avoid getting a LowFeeTransaction error from the pool

* rustfmt

pool/src/pool.rs

@@ -567,6 +567,11 @@ where
 			// TODO evict old/large transactions instead
 			return Err(PoolError::OverCapacity);
 		}
+
+		// for a basic transaction (1 input, 2 outputs) -
+		// (-1 * 1) + (4 * 2) + 1 = 8
+		// 8 * 10 = 80
+		//
 		if self.config.accept_fee_base > 0 {
 			let mut tx_weight = -1 * (tx.inputs.len() as i32) + (4 * tx.outputs.len() as i32) + 1;
 			if tx_weight < 1 {
@@ -1055,7 +1060,7 @@ mod tests {
 
 	fn test_setup(dummy_chain: &Arc<DummyChainImpl>) -> TransactionPool<DummyChainImpl> {
 		TransactionPool {
-			config: PoolConfig{
+			config: PoolConfig {
 				accept_fee_base: 0,
 				max_pool_size: 10_000,
 			},