Remove python 3.5 from circle CI

.circleci/config.yml

tests/beem/test_account.py

tests/beem/test_cli.py

tests/beem/test_constants.py

tests/beem/test_hivesigner.py

tests/beem/test_instance.py

tests/beem/test_steem.py

tests/beem/test_steemconnect.py

tests/beem/test_storage.py

tests/beem/test_testnet.py

tests/beem/test_wallet.py

tests/beemapi/test_steemnoderpc.py

tests/beemapi/test_websocket.py