Add config setting to disable mandatory tokens check in mailings

As per a previous discussion (with Lobo IIRC), add a configuration
setting to disable the check for presence of mandatory tokens when
sending mailings.

This setting is implemented as a negative option, i.e. ticking the
option disables the check. We could also reverse the logic, so that
ticking the option enables the check instead; and set it to on by
default... Not sure which is preferable -- I guess that's mostly a
matter of taste.
Merge pull request #1505 from sfe-ev/disable_mandatory_tokens

Add config setting to disable mandatory tokens check in mailings
CRM-13294 fix membership to support IN format on contact_id

Conflicts:

	tests/phpunit/api/v3/MembershipTest.php
test fix on api_v3_ContributionTest.testCompleteTransaction api_v3_ContributionTest.testCompleteTransaction
Add Options to Membership search to print labels & send letters
Merge pull request #1526 from eileenmcnaughton/master

CRM-13294 - extra fix + test fix
fix git code mgmt mistake
Merge pull request #1527 from eileenmcnaughton/master

fix git code mgmt mistake
CRM-13284 fix empty billing profile for autofill
CRM-13284 fix autofill for event page for anon users
CRM-13187 - migrate settings from domains table  to word replacement table

----------------------------------------
* CRM-13187: hrui: Change breadcrumb from "CiviCRM" to "CiviHR"
  http://issues.civicrm.org/jira/browse/CRM-13187
Merge branch 'master' into reports
CRM-13125 - url filter support for type float
Merge pull request #1529 from deepak-srivastava/reports

CRM-13263 - notice fix, CRM-13125 - url filter support for type float
Added missing menu row in edit profile
Merge pull request #1530 from vivekarora/CRM-13114-Fixed

CRM-13114 - Added missing menu row in edit profile
Merge pull request #1521 from yashodha/4.4.CRM-13212

more fixes for CRM-13212
rename Job DAO to MailingJob
patch for CRM-13290
Merge pull request #1532 from yashodha/CRM-13290

patch for CRM-13290