Fixed some problems wtih new version of vagrant.
Added metadata to packer-generated vagrant box.

This was done while debugging the vagrant issues but seems worthwhile
to keep anyways.
Removed old playbook.yml file.

Took me some time to realise it's not doing anything anymore. I wonder
how it got into source control in the first place...
Added mangoengine as submodule.

I created a new package galah.third_party that houses it. I did this
because making changes to mangoengine and testing them with Galah was
a serious chore that usually involved the scp utility. Hopefully this
will improve things.

There's a little bit of import hackery to make any packages in
third_party's subdirectories importable.
Fixed mangoengine imports to point at sub-repo.
Fixed inconsistent use of VM IDs.

The VMFactory stores the ID of the VM it's currently doing work on,
but the code did not agree on how that ID was stored. This change
makes everything consistently tread the ID as a local ID stored as
an integer.
Updated mangoengine with new bugfix.

This prevents errors from occuring when an IntegralField with a None
value is validated.