CRM-14896 - remove obsolete markup from AdditionalParticipant.tpl

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* CRM-14896:
  https://issues.civicrm.org/jira/browse/CRM-14896
Merge pull request #3535 from davecivicrm/CRM-14896

CRM-14896 - remove obsolete markup from AdditionalParticipant.tpl