Agam: DB backup tweaks (twerks)

- Added gzipping of the backup file
- Added the removal of yesterday's backup file from local
- Added client_secrets.json (config file of db_backup.sh) to
	.gitignore
- Made slight style changes to the upload_to_dropbox script
Merge pull request #11 from agamrafaeli/master

Agam: DB backup tweaks (twerks)