Improved gps location device simulation

[joelhulen]

Type of change?

• [x] Bug fix
• [ ] New feature
• [x] Enhancement
• [ ] Breaking change (breaks backward compatibility)

Description, Context, Motivation

The previous version never actually changed the truck's location after the first pass. This version randomizes the changed distance, plus it adds a rounding function that handles the positive and negative values of the lat/long coordinates equally well. This results in an improved randomized route for the trucks. Not 100% realistic (data would need to be incorporated for that), but good enough for a simulation.

Checklist:

• [ ] All tests passed
• [x] The code follows the code style and conventions of this project
• [ ] The change requires a change to the documentation
• [ ] I have updated the documentation accordingly

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This change is 

[dluc]

@joelhulen thanks for the PR, we're looking into it

[dluc]

@peterfelts could you look at this PR?