Use globs, set nullglob, and remove stdout redirection for import
Merge pull request #333 from rhy-jot/2013-11-20/backup-find-to-glob

backup:export: find -> glob
Add a version command.

The git tag/revision is saved when running "make install", and can be
displayed using "dokku version".
Use a hardcoded version if git revision is not available.
Add the date and time of installation if version is hardcoded.