added provider and staff name to csv export #3245

Duplicated methods in helpers/application_helper
to help transform the staff_id attribute into
an actual name. I'd like to refactor this
duplication out, but I'm not sure including
the helper in the model is a good idea.
Merge pull request #69 from NUBIC/bug_3245_update_columns_in_contact_search_export_csv

added provider and staff name to csv export #3245