Virtualbox 5 Support

[lxe]

I install Virtualbox version 5 via Caskroom to use as my dinghy vagrant provider, but when I do dinghy up, I see the following error:

❯ dinghy up -p virtualbox
The provider 'virtualbox' that was requested to back the machine
'dinghy' is reporting that it isn't usable on this system. The
reason is shown below:

Vagrant has detected that you have a version of VirtualBox installed
that is not supported. Please install one of the supported versions
listed below to use Vagrant:

4.0, 4.1, 4.2, 4.3
/usr/local/Cellar/dinghy/3.0.3/cli/dinghy/vagrant.rb:21:in `up': There was an error bringing up the Vagrant box. Dinghy cannot continue. (RuntimeError)
    from /usr/local/Cellar/dinghy/3.0.3/cli/cli.rb:33:in `up'
    from /usr/local/Cellar/dinghy/3.0.3/cli/thor/lib/thor/command.rb:27:in `run'
    from /usr/local/Cellar/dinghy/3.0.3/cli/thor/lib/thor/invocation.rb:126:in `invoke_command'
    from /usr/local/Cellar/dinghy/3.0.3/cli/thor/lib/thor.rb:359:in `dispatch'
    from /usr/local/Cellar/dinghy/3.0.3/cli/thor/lib/thor/base.rb:440:in `start'
    from /usr/local/bin/dinghy:5:in `<main>'

[lxe]

I'm fairly certain this is a Vagrant error... investigating

[lxe]

I think this is because I have an old version of vagrant...

❯ vagrant -v
Vagrant 1.7.2

The latest one is 1.7.4 as of right now. I upgraded Vagrant and it works. Sorry for the trouble!