Audit of ao2_iterator_init() usage for v1.8.

Fixes numerous reference leaks and missing ao2_iterator_destroy() calls as
a result.

Review: https://reviewboard.asterisk.org/r/1697/
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Merged revisions 352955 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 352956 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@352957 65c4cc65-6c06-0410-ace0-fbb531ad65f3