Use boxes from OBS instead of vagrant cloud

[denisok]

https://build.opensuse.org/project/show/home:jloehel:vagrant:images has an updated boxes, they are updated automatically.

• remove boxes dir from the project
• add code that will take box link from yml config (like in PR #17 ) and check checksum (link also in yml file)
• if checksum is different from remote - remove old and add new box

So we would workaround versioning for the boxes, as kiwi doesn't support that and we don't want to push some boxes to the cloud.

The only thing that need to be noticed - "vagrant box remove" doesn't remove libvirt image, that should be also removed, as new box will not replace the image:

vagrant box remove SUSE/SLE-15                                                               
Removing box 'SUSE/SLE-15' (v0.0.1) with provider 'libvirt'...                                       
Vagrant-libvirt plugin removed box only from you LOCAL ~/.vagrant/boxes directory                    
From libvirt storage pool you have to delete image manually(virsh, virt-manager or by any other tool)