tests/integration/cli: Add CLI tests.
tests/integration/cli: Add CLI tests.

Add the following tests:

test_cli_missing_discovery_contract_address
test_cli_wrong_rpc_endpoint
test_cli_wrong_network_id_try_mainnet
test_cli_swap_registry_address_with_discovery_address
test_cli_full_init
test_cli_registry_address_without_deployed_contract
test_cli_missing_data_dir
test_cli_version
test_cli_malformed_registry_address
test_cli_missing_keystore_path
test_cli_missing_password_file_enter_password
test_cli_missing_nat

that test most of the CLI used parameters and wrong scenarios.

There is also a disabled test case DISABLE_test_cli_eth_client_communication
that times out due to functionality removed after commit 2ec2bad.

Refs: #1408

hackaugusto/raiden,hackaugusto/raiden