CRM-14708 accept POSTs without x_cust_id based on missing contact_id problem & existing logic making it optional

Conflicts:
	CRM/Core/Payment/AuthorizeNetIPN2.php
CRM-14718 early return on already processed subscription updates
CRM-14760 - ensure prefix/suffix is updated via profile update

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* CRM-14760: updating individual prefix via profile fails
  https://issues.civicrm.org/jira/browse/CRM-14760
CRM-12856 hack to stop problems arising from mis-use of locks - need to review correct approach
Merge pull request #3318 from eileenmcnaughton/CRM-14718

CRM-14718 return early for already-handled-notifications
Merge pull request #3390 from eileenmcnaughton/CRM-12856

CRM-12856 short-term fix - stop double mailings arising from core locks
Merge pull request #3292 from eileenmcnaughton/CRM-14708

CRM-14708 accept POSTs without x_cust_id based on missing contact_id … …
Merge pull request #3383 from jmcclelland/prefix-id-update-via-profile

Prefix id update via profile
CRM-14836 - fix mispelling of activities.

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* CRM-14836: Activities is misspelled on activity delete confirmation page
  https://issues.civicrm.org/jira/browse/CRM-14836
Merge pull request #3470 from jmcclelland/activities-typo

Activities typo
CRM-14838 tokens not working when value is rendered as an integer