Added a very important call removeObserver: to balance the addObserver in performInstallGrowl. Its lack leads to an intermittent crash when using Growl-WithInstaller.framework and the following occurs:  1. Growl is previously installed (this is an upgrade)  2. System Preferences is currently running  3. Growl is installed via the update prompt  4. System Preferences is then quit while the host application in which Growl-WithInstaller was being used is still running.
Added a very important call removeObserver: to balance the addObserver in performInstallGrowl. Its lack leads to an intermittent crash when using Growl-WithInstaller.framework and the following occurs:
 1. Growl is previously installed (this is an upgrade)
 2. System Preferences is currently running
 3. Growl is installed via the update prompt
 4. System Preferences is then quit while the host application in which Growl-WithInstaller was being used is still running.

--HG--
extra : convert_revision : svn%3A99687598-2e92-11dd-8019-fe7b9d601d1b/trunk%404706

incbee/Growl,PersonifyInc/growl,PersonifyInc/growl,PersonifyInc/growl,incbee/Growl,PersonifyInc/growl,incbee/Growl,incbee/Growl,PersonifyInc/growl,incbee/Growl