cli: replace testnet with chain and return network name as per BIP70.

test/functional/interface_bitcoin_cli.py

@@ -65,7 +65,7 @@ class TestBitcoinCli(BitcoinTestFramework):
         assert_equal(cli_get_info['connections'], network_info['connections'])
         assert_equal(cli_get_info['proxy'], network_info['networks'][0]['proxy'])
         assert_equal(cli_get_info['difficulty'], blockchain_info['difficulty'])
-        assert_equal(cli_get_info['testnet'], blockchain_info['chain'] == "test")
+        assert_equal(cli_get_info['chain'], blockchain_info['chain'])
         if self.is_wallet_compiled():
             assert_equal(cli_get_info['balance'], wallet_info['balance'])
             assert_equal(cli_get_info['keypoololdest'], wallet_info['keypoololdest'])