Do not delete the database dump if --skip-db

If the --skip-db flag is set we do not want to dele the database.sql file that
we didn't create.
Merge pull request #2 from mogensen/patch-1

Do not delete the database dump if --skip-db
Removed newline at end of file
Added --skip-fs to skip creating filesystem archive
Added initial support to exclude MySQL table data from backup
Fixed errors due to possibly undefined variables