Better API to catch remote exceptions

- Rename ErrorReply to RemoteError.
- Add __str__, __repr__ to RPCError for better message display.
- Allow catching remote exception by using RemoteError.<remote error class name>.
Merge pull request #59 from mouadino/remote-exception

Better API to catch remote exceptions
Fix logging madness

- Log lymph.ping request as debug
- Workaround gevent to log http requests using python logging (https://github.com/gevent/gevent/issues/106)
Merge pull request #58 from mouadino/fix-logging

Fix logging madness
Log uncaught exceptions to the lymph logger
Merge pull request #61 from emulbreh/fix-web-error-log

Log uncaught exceptions to the lymph logger
Fix status argument in werkzeug Response
Merge pull request #62 from mouadino/fix-response-status

Fix status argument in werkzeug Response