User alerts; level/color start/stop events; set_log_file_path()

[UpDryTwist]

This PR is dependent on PR #2531 in OpenZWave/open-zwave, which adds support for setting the log file path.

This change is necessary to fully support the RGBGenie, a switch that sends various light control commands.

The PR adds three enhancements:

1. Support receiving user alerts (such as alerts about failures to update the config, etc.). Turns them into notifications.

2. Support receiving level change and color change start/stop events. A switch can send commands to start incrementally changing the level (for dimming) or the color (for hue adjustment).

3. Support setting the log file path with set_log_file_path(). This can be used to move the log file to, e.g., /var/tmp (or somewhere else) if you need to not be writing in the current location.