CRM-13978 - Replaces PR 2219 which had all the right changs BUT omitted the activity tagset filter.

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* CRM-13978: search on activity result field
  http://issues.civicrm.org/jira/browse/CRM-13978
Merge pull request #2246 from davecivicrm/CRM-13978

CRM-13978 - Replaces PR 2219 which had all the right changs BUT omitted ...