Add colored logging support

[bgottula]

Add support for colored log messages.

The coloredlogs package seems promising:

https://github.com/xolox/python-coloredlogs
https://coloredlogs.readthedocs.io/en/latest/
https://pypi.org/project/coloredlogs/

[bgottula]

Added. I wanted to more closely match the colors spdlog uses by default, but unfortunately coloredlogs doesn't support applying colors to the level field that are a function of the level, as best I can tell. Only the actual log message can have a level-dependent color. But that's a very minor concern. Aside from that I think the log messages emitted to stdout are easier to quickly scan.