Make the crontab use the correct path and bash

Signed-off-by: Jeroen van Baarsen <jeroenvanbaarsen@gmail.com>
Merge pull request #132 from intercity/jb-fix-backup-path

Make the crontab use the correct path and bash
Add version 0.1.0 of sysadmins: a way to add sudo users
Make sudo work like Ubuntu's defaults.

* Use a group called "admin"
* Require a password for sudo.

Requiring a password breaks Vagrant's provision and setup
and as such, we don't require a password in Vagrant.
Add the current changes to the changelog
Quoting according to houd-ci with double (") quotes
Make username the key of the list of sysadmins.
Change licence to MIT
Move sysadmins out of base role.

Don't run it by default, but make it a role.