Corrections for Vagrant 1.6.3 and vagrant-berkshelf 2.0.1

Here are my changes to make the Vagrantfile work with Vagrant 1.6.3 and the updated vagrant-berkshelf 2.0.1 plugin.
Tested with Packer 0.6.0, Vagrant 1.6.3, VirtualBox 4.3.12 on Mac OSX 10.9.3. Created an Ubuntu 13.10 box.
My box is still provisioning, but everything looks good so far.

But there is a known issue: The vagrant-berkshelf plugin could not be installed on a Windows host at the moment. Tried this today on my work machine and gave up with already known issues (installing dependency dep-selector-libgecode or something like that). Mac and Linux hosts work fine.