Use LogRecords better - will lead to better grouping in Rollbar

- use the unformatted message string, instead of the formatted one
- include the message args in body.message.body.args
- include other properties of the [LogRecord](https://docs.python.org/2/library/logging.html#logrecord-objects) in body.message.body.record
Merge pull request #31 from rollbar/more-logrecord-details

Use LogRecords better - will lead to better grouping in Rollbar