CRM-13965 - label, status and display changes for AdditionalPayment form.

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* CRM-13965: Record additional payments or refunds for pending-pay later OR partially paid event registrations
  http://issues.civicrm.org/jira/browse/CRM-13965
Merge pull request #2516 from davecivicrm/CRM-13965

CRM-13965 - label, status and display changes for AdditionalPayment form...