Local backup

This adds a new directory, localBackup, to the top level of the WattDepot project. localBackup contains three files intended for use on Linux systems to retain a monthly backup and all backups from the last 7 days (604800 seconds).

* **wattdepot_backup_script.sh**: Backs up the Wattdepot database and other files into a .tar.gz archive, which it places in /wattdepot-backups on the system.
  * This script enables wattdepot_backup_script.sh to be run automatically. 
  * On the first day of the month, it copies the backup it makes to a /wattdepot-backups/monthly directory. 
  * Daily backups are deleted after 7 days with the user's permission.
  * If the script is run with --delete-auto, it deletes daily backups more than 7 days old without asking.
* **wattdepot_backkup_runner.sh**: Runs wattdepot_backup_script.sh with its --delete-auto option and a value set for the PGPASSWORD environment variable. 

* **localBackup/wattdepot_postgresql_backup_procedure.txt**: Instructions for the use of the files.

This also adds a **.gitattributes** file to the top-level directory to force all commits of text files to have Unix line endings. It is identical to the current Makahiki .gitattributes.