Preferred source should be selectable and not only CIEL

It should be possible to change the preferred source to PIH or AMPATH.  The UI currently allows only CIEL as a preferred source.

Work:

1. Identify all places where CIEL is hard coded as preferred source
2. Fix each of those so that a user can specify something other than CIEL as preferred.  For MVP, the sources are CIEL, PIH or AMPATH