CiviMail: Make it obvious that {action.optOutUrl} fulfils {action.optOut} requirement

Currently mailings say that they require the existence of the

{action.optOut} token, while it's actually either {action.optOut}

or

{action.optOutUrl}

. As we strongly prefer people to use the latter (this way the back channel is HTTP based, instant and not handled by the CiviMail Processor), we should make sure people know that they may (and that they actually use) the latter instead of the former.

I've updated the Help for that page, the requiredTokens validation error message and the following wiki pages to "recommend" optOutUrl action token. Also removed obsolete references in the wiki pages and the .hlp file to unsubscribe being required

http://wiki.civicrm.org/confluence/display/CRMDOC/CiviMail+Action+Tokens