Fix sensor unit handling

[cryptk]

Did some general cleanup around the handling of constants in order to resolve #79 while removing some of the custom constants that duplicated built-in constants.

Removed all instances that manually updated the entity state and replaced them with updates to native_value instead allowing Home Assistant to actually perform unit conversions resolving #80

[cryptk]

I'm not sure why the commit message isn't properly linking this PR to both #79 and #80, but if/when this PR is accepted, both issue #79 and #80 need to be marked as resolved

[cryptk]

@mrk-its any chance I can get a review on this? This should resolve the issue of the integration showing the distance in KM no matter if you select KM or MI as your units.

[mrk-its]

@mrk-its any chance I can get a review on this? This should resolve the issue of the integration showing the distance in KM no matter if you select KM or MI as your units.

Sure, taking a look!

[mrk-its]

looks good!

[codyc1515]

Is this ready to merge?

[cryptk]

@mrk-its sorry for the delay, had a few health issues. I made the change you requested, can I get a new review and possibly a merge? I'm running this version locally, and it starts up with no errors, and it should be fine, but there currently aren't any storms outside for me to validate the second commit.

[cryptk]

Hey @mrk-its wanted to bring this up again. I made the change that you requested, would be great to get this merged in to resolve the warnings in the logs about the upcoming deprecations.

[jrbenito]

This also fixes #82

[bakerkj]

@cryptk & @mrk-its I can confirm running with this PR eliminated all warnings for me as well.

[mrk-its]

Thanks @cryptk and sorry it took so long