Cleaned most warning OSX OpenAFS preference and completed the AFSBackgrounder implem...

Cleaned most warning OSX OpenAFS preference  and completed the AFSBackgrounder implementation

At startup the preference pane check for the presence in ~/Library/LaunchAgents of the file  it.infn.lnf.network.AFSBackgrounder.plist that. The agent could be started in OpenAFS preference pane view.
AFSBackgrounder has replaced the NSMenuExtra, when it doesn't quit well launchd restart it. AFSBackgrounder can be used also for other work, for now, at login it check the user preference for get token.
Has been made some refactoring in code for remove most warning.
The unused think are been delete from project.

Reviewed-on: http://gerrit.openafs.org/263
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>