fix save external asset bug. (#1218)

fix save external asset bug. (#1218)

* the transaction output amout prohibit set zero

* add network access control api

* format import code style

* refactor

* code refactor

* bug fix

* the struct node_info add json field

* estimate gas support multi-sign

* add testcase of estimate gas

* add testcase

* bug fix

* add test case

* test case refactor

* list-tx,list-address,list-utxo support partition

* list-addresses list-tx list-utxo support pagging

* refactor pagging

* fix save asset

* fix save external assets

* remove blank