Stability (#324)

* propagate rootcause of JsonRpcException
* increase pool size
* Log WsConnectionImpl exceptions

src/test/groovy/io/emeraldpay/dshackle/rpc/NativeCallSpec.groovy

@@ -176,7 +176,7 @@ class NativeCallSpec extends Specification {
         nativeCall.rpcReaderFactory = Mock(RpcReaderFactory) {
             1 * create(_) >> Mock(RpcReader) {
                 1 * read(new JsonRpcRequest("eth_test", [], 10)) >> Mono.error(
-                        new JsonRpcException(JsonRpcResponse.Id.from(12), new JsonRpcError(-32123, "Foo Bar", "Foo Bar Baz"), null, true)
+                        new JsonRpcException(JsonRpcResponse.Id.from(12), new JsonRpcError(-32123, "Foo Bar", "Foo Bar Baz"), null, true, null)
                 )
             }
         }