Iottalk-py

- dai: fix multiprocessing pickling issue on windows (31)
- fix pytest-cov version (34)
- dai: print traceback for exception from on_data (33)
- req: update iottalk-paho-mqtt to 1.4.0.dev3 (32)
- Propagate context for on_* callback functions (35)
- dai: Fix regex bug (37)
- dai: fix on_disconnect parameters (38)
- allow user set the push interval as a callback function to get dynamic interval (46)

- Add support for Python 2 (25)
- Add support for Python 3.4 (25)
- Improve compatibility for old setuptools (26)
- DAI: support loading from absolute path (20)

- Implement device state machine (14) flow.

Changes
DAI persistent binding (https://github.com/IoTtalk/iottalk-py/pull/13) is implemented.
There is a new option for IDA, `persistent_binding = True` in your IDA.