Disregard thresholds for jobs with multiple possible running sites. For monitoring purposes, report one random site in the possible site list as the 'pending' site.
Record location changes in WMBS and Couch

Whenever a job starts running, check the CMS site
where it started and store in WMBS and the transition
record in the JobDump in CouchDB. This ensures that
WMStats has the proper monitoring information and
runtime errors are attributed to the right site.

Fixes #3971
Fixes #3972