Bug 33428: (follow-up): Default to searching 'standard' fields

Bug 33428: (follow-up): Default to searching 'standard' fields

Before this patch set, a search for patrons from article requests or
reserves would search the attributes by default. They were not considered
'standard' searches, however.

This patch simply defaults to searching the 'standard' fields unless a value is passed

To test:
1 - Apply other patches
2 - Have patrons with searchable attributes
3 - From a title, click the holds or artickle requests tab
4 - Search for the attribute values and confirm patrons are not returned
5 - Apply this patch
6 - Search again, patrons are now returned

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>