Don't include logger.h in asterisk.h by default as it is causing problems building

app_voicemail.  Instead, include it where it is needed.  This turned out to be a
relatively minor issue because other headers include logger.h as well.

Need to test -addons before merging this back to 1.6.0.

(closes issue #13605)
Reported by: tomo1657
Patches: 
      13605_seanbright.diff uploaded by seanbright (license 71)
Tested by: mmichelson


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@148200 65c4cc65-6c06-0410-ace0-fbb531ad65f3