AMI/ARI: Update version to 2.5.0/1.5.0 respectively

This is to support the backwards compatible changes made in the next version
of Asterisk.
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Merged revisions 420805 from http://svn.asterisk.org/svn/asterisk/branches/12
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Merged revisions 420808 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@420811 65c4cc65-6c06-0410-ace0-fbb531ad65f3