Implement jobsites

# Definition
a Jobsite:
* belongs to: Organization
* has many: Map (only one active/primary)
* has fields: `id`, `name`, `address`, `city`, `state`, `postal_code`, `country`, `acreage`, `linear_feet`, `type`, `status`, `lat`, `long`

# Planning
* has many?: Estimate, ServiceItem
* belongs to many?: Contract
* how to save active/primary map?
   * attach to Contract to "set in stone"?