Catches fog exception when machine could not be found
Catches the following exception to prevent stack from being displayed:
Bringing machine 'default' up with 'libvirt' provider...
/home/teto/vagrant-libvirt/vendor/bundle/ruby/1.9.1/gems/fog-1.20.0/lib/fog/libvirt/models/compute/volume.rb:84:in `default_pool_name': No storage pools are defined (Fog::Errors::Error)
    from /home/teto/vagrant-libvirt/vendor/bundle/ruby/1.9.1/gems/fog-1.20.0/lib/fog/libvirt/models/compute/volume.rb:33:in `initialize'
    from /home/teto/vagrant-libvirt/vendor/bundle/ruby/1.9.1/gems/fog-1.20.0/lib/fog/core/collection.rb:114:in `new'
Merge pull request #167 from teto/fixes

Fixes