Add 'fullbackup' script that forces a full backup.

I've added this extra script so it's very easy to add a slightly more
robust backup cronjob set.  For example, with this fullbackup script,
you can run the regular, incremental 'backup' script daily, then the
'fullbackup' script weekly. This way you get 4 sets of incremental
backups monthly.
Lint/PEP8 stuff

Just satisfying some PyLinter stuff. Apologies if it conflicts with the
author's style.
Fixed tests for me by using '\n' instead of '\r'.
pep8
Added a test for fullbackup.
typo
Merge pull request #7 from collective/independent-full-backup

Independent full backup