DjangoPBX House keeping application added.

I didn't like having add-on shell scripts for ordinary house keeping tasks. So now we have an application that takes care of many of these tasks.

• Making database and file backups
• Removing json content form XML CDR records
• Converting .wav files to mp3s to save on storage space
• Removing call recordings and voicemails over X days old
• Removing log files over X days old
• Removing XML CDR records over X days old.

The time limit for actions like removing call recordings, voicemails and CDR records can be set at the domain level so they can be different for each customer.

The default settings that control housekeeping can be found in the Housekeeping category.
The default django-pbx user crontab file has been updated to drive these tasks automatically overnight.