flake8 cleanup

This cleans up whitespace and imports but does leave some things alone.

```
./backends/bitcoind/blockchain_processor.py:15:1: F403 'from utils import *' used; unable to detect undefined names
./backends/bitcoind/deserialize.py:8:1: F403 'from utils import *' used; unable to detect undefined names
./backends/bitcoind/deserialize.py:220:1: F841 local variable 'pubkeys' is assigned to but never used
./backends/bitcoind/deserialize.py:242:1: F841 local variable 'start' is assigned to but never used
./backends/bitcoind/deserialize.py:368:1: F841 local variable 'num' is assigned to but never used
./backends/irc/__init__.py:175:1: F841 local variable 'params' is assigned to but never used
./backends/libbitcoin/__init__.py:4:1: F401 '_3' imported but unused
./backends/libbitcoin/h1.py:23:301: E501 line too long (546 > 300 characters)
./backends/libbitcoin/history.py:429:301: E501 line too long (1271 > 300 characters)
./backends/libbitcoin/history.py:432:301: E501 line too long (551 > 300 characters)
./backends/libbitcoin/history.py:467:301: E501 line too long (550 > 300 characters)
./transports/stratum_http.py:173:1: F841 local variable 'e' is assigned to but never used
./transports/stratum_http.py:221:1: F841 local variable 'e' is assigned to but never used
./transports/stratum_http.py:283:1: F841 local variable 'vi' is assigned to but never used
./transports/stratum_http.py:316:1: F841 local variable 'vi' is assigned to but never used
./transports/stratum_http.py:345:1: F841 local variable 'raw_response' is assigned to but never used
./transports/stratum_tcp.py:141:1: F841 local variable 'message_id' is assigned to but never used
./transports/stratum_tcp.py:142:1: F841 local variable 'method' is assigned to but never used
```