[#706] PEP8 Compliance

If you want me to actually remove the changes from `dht.py`, `market.py` and `transport.py` let me know.
I can also add a test for PEP8 compliance.
line too long.
I could make it one of these:

```python
shipping_address_json = json.dumps(self.get_shipping_address())
order_dictionary = {
    "order_id": order_id,
    "state": "Sent",
    "signed_contract_body": contract,
    "market_id": self.market_id,
    "shipping_address": shipping_address_json,
    "updated": time.time(),
    "merchant": contract_data_json['Seller']['seller_GUID'],
    "buyer": self.transport.guid}
try:
    self.db.insertEntry("orders", order_dictionary)
except Exception as e:
    self.log.error('Cannot update DB %s', e)
```

or if an Exception might occur in the dict creation:

```python

try:
    shipping_json = json.dumps(self.get_shipping_address())
    merchant_json = contract_data_json['Seller']['seller_GUID']
    order_dictionary = {
        "order_id": order_id,
        "state": "Sent",
        "signed_contract_body": contract,
        "market_id": self.market_id,
        "shipping_address": shipping_address_json,
        "updated": time.time(),
        "merchant": merchant_json,
        "buyer": self.transport.guid}
    self.db.insertEntry("orders", order_dictionary)
```