Python 3 Support in 2017

[alansnow21]

Python 2 EOL in 2020 (https://pythonclock.org/).

As such, to assist app developers in modifying code to be 2/3 compatible, it would be a great New Year's goal to modify Tethys Platform to be Python 2/3 compatible by the end of the year.

[swainn]

I agree with alansnow21's call to action. The discussion I would like to pose to the forum is with only 3 years of Python 2 support, should would it be worth it support both Python 2 and 3? Or should we migrate to Python 3 only support?

Also, here is the official guide for migrating to Python 3:

https://docs.python.org/3/howto/pyporting.html