Add site status to the Incident Management macro functionality and as a return field in the Device Status API.

Site Status was a development item to provide a status of Up, Up/Degraded, Up/On-Backup, Down based on a variety of agreed upon interface tags. We would like to have that site status be made available in 2 ways:
1) As a "macro" available to be included in Incident Management Alert formats and Rules.
2) As a new field to be automatically included in Device Status API result payloads.