Move district and maintenance_provider classes to Transit where they belong
Cleanup asset class removiing district and maintenancw_provider references and move the purchase_price, purchase_date, in_service_date, purchased_new, and expected_useful_life properties to asset.
Remove DS_Store file
Remove depreciation calculators
Remove service type from core -- this belongs in Transit
Merge branch 'master' of https://github.com/camsys/transam_core
Move depreciation work to accounting mixin
Remove depreciation items from Policy
Enable loading nav components from the app
Merge branch 'master' of https://github.com/camsys/transam_core