Add python3 support

This adds python 3 support, but also makes minor changes

- README rewritten using markdown
- Increased default timeout value (was causing timeout often on my device)
- Handle `EVENT_RX_FAIL_GO_TO_SEARCH` event like `EVENT_TRANSFER_TX_FAILED` (raise `TransferFailedException` to support retrying) 
- [PEP8](https://www.python.org/dev/peps/pep-0008/) compliant formatting

Tested using antfs-cli on python 2.7.8 and python 3.4.1 with the Garmin Forerunner 610
I thought at the beginning that the timeout issues came from this value, but it didn't, so i'll remove this comment.

To fix timeout issues, we should handle more possible response code [here](https://github.com/Tigge/openant/blob/master/ant/easy/filter.py#L30-L58) dans display a proper user message based on effective device response.