* do not allow update votes with both empty lists
* fix error messages
* check number of sons against votes number in account_object
* Update error message
* refactor cli tests
* update_son_votes tests
* list_sons test
* test changes in get_global_properties() result
* fix generate_block failure
* fix update_son_votes test
* improve update_son cli test
* fix linking errors
* refactor select_top_fifteen_sons test
* refactor other son cli tests to use son_test_helper
* create_vesting call in wallet_api
* test fix
* fix create_son in wallet_api and cli tests