Add related contact to offices index

Displays related_contact &/or general inquiries contact info on offices index page.

- Moves contact-us code into macro for reuse here. (Macro currently still lives in contact-us directory)
- Uses single query to fetch both related_contact & 'general_inquiries'. May need to change if there is a preference in display order.
You're talking about this right?

![image](https://cloud.githubusercontent.com/assets/1093373/5477261/c3b873c0-85f7-11e4-81df-900acda35d3c.png)

I think that it's meant to represent the primary point of contact and not the contact named "general contacts".