Make changes to the vagrant box so translations can be built and maintained

[kd-ods]

We're making use of Transifex to translate the schema and docs. See the readme here

Users need to be able to:

• Checkout and build any release of the docs in any available language (meaning that both the theme and the docs would be built in the given language).
• Push changes to the English language version of the docs, for a given docs branch, to the related Transifex project for translation.

Changes may need to be made to the vagrant box to enable these tasks.

[kd-ods]

@odscjames I don't have permissions to assign this issue, but need to assign it to you!

[odscjames]

Assigned to me, tho is @rhiaro looking at this?

[rhiaro]

@odscjames I need to consult with you about the vagrant side of things please!

[odscjames]

@rhiaro Sure, let me know when you want to chat or add things here!

[stevenday]

From #45 this potentially includes adding gettext and pybabel to the packages. Presumably also the transifex client.