vagrant-rebox should install default (insecure) pubkey...

[David Lindes]

When doing vagrant up, the default pubkey from https://github.com/mitchellh/vagrant/tree/master/keys is removed, and replaced with a newly generated key. If I then do vagrant-rebox, vagrant destroy, and vagrant up, the new VM can't be accessed using SSH keys, because the default key isn't there, and the destroy got rid of the new privkey.

So, my thought is to add an (optional?) ability to re-insert the insecure pubkey before doing the reboxing.

Also, I seem to need to run vagrant halt, but currently don't. Adding that after the key re-install would be ideal.