CrimeRateUpdate class should use dependency injection vs. singleton

[ldicker83]

It's easy to use the NAS2D::Utility class to get the StructureManager instance (can be seen here) but this comes at the cost of not being transparent where this information comes from and tightly coupling the CrimeRateUpdate with a poorly defined/undefined dependency.

This can be done during the construction of the object or with a dedicated function for it. It can also be done by modifying the update() parameter list to require the dependency.