Double port 80 mappings in vagrant VirtualBox provider

[ruebot]

Looks like we're getting duplicated port 80 mappings for the VirtualBox provider since we've merged #52.

==> default: Forwarding ports...
    default: 8080 => 8080 (adapter 1)
    default: 8181 => 8181 (adapter 1)
    default: 3306 => 3306 (adapter 1)
    default: 5432 => 5432 (adapter 1)
    default: 80 => 8000 (adapter 1)
    default: 80 => 80 (adapter 1)