CLC-3736 Start caching person attributes from campus DB

https://jira.ets.berkeley.edu/jira/browse/CLC-3736

This refactoring is a preparatory step. The uncached parsed "get_person_attributes" query was already called from three different code locations (twice in a row from Financials::Proxy), & the CLC-3736 fix will add it to the MyAcademics module as well.