Remove postfix dependency

The postfix dependency was introduced because Drupal try to send an email with the password to the site admin.

With version 7.21 it seems it don't do this anymore, so we can remove this dependency.
Update Vagrantfile to version 2

Vagrant updates some options of the Vagrantfile with version 1.x. This change will update the existent vagrant file which is know as version 1 to version 2
Remove my own vm box and use the origin.
Merge branch 'refs/heads/Vagrantfile2'