append a newline to the LinodeException message

```
[domain.list.lol] The requested class does not exist
Traceback (most recent call last):
  File "/tmp/bleh", line 4, in <module>
    for domain in linode.domain.list.lol():
  File "/Users/jchen/.venvs/linode/lib/python3.4/site-packages/linode-0.4.1-py3.4.egg/linode/api.py", line 27, in __call__
  File "/Users/jchen/.venvs/linode/lib/python3.4/site-packages/linode-0.4.1-py3.4.egg/linode/api.py", line 76, in _worker_func
  File "/Users/jchen/.venvs/linode/lib/python3.4/site-packages/linode-0.4.1-py3.4.egg/linode/api.py", line 69, in _request
linode.api.LinodeException: ('domain.list.lol', [{'ERRORMESSAGE': 'The requested class does not exist', 'ERRORCODE': 3}])
```