Add support for vagrant-cachier plugin

[hectcastro]

This pull request adds basic support for the vagrant-cachier. There is no support for scopes or targeting specific buckets yet.

Attempts to resolve #26.

[tknerr]

👍

[sethvargo]

After discussion, we think these patterns could quickly grow out of scale. Instead of handling all the special edge cases, I've created #51 to allow users to specify a full Vagrantfile which can be fully customized.

[fnichol]

If this setting must go in each Instance's Vagrantfile and not somewhere globally, there's now support for specifying your own custom Vagrantfile ERB template, as of cc75795

[hectcastro]

Thanks, @fnichol. :)

[fnichol]

@hectcastro No problem, and thanks for your work on the Riak-related cookbooks. Was pumped to see a pretty .kitchen.yml in there 😄