Editable SEO fields

![fronst-tool](https://cloud.githubusercontent.com/assets/1147913/2888712/6e0aa0c6-d510-11e3-9ef4-049b5723cf20.png)

Adds these fields per container, into the config:
```
section
webTitle
title
description
priority
```
Changes the LHS column to an alphabetical list of all containers. The concept of "orphaned containers" is removed; they are no longer persisted (they were just accumulating and being ignored).

![fronst-tool](https://cloud.githubusercontent.com/assets/1147913/2888683/9ed5ef90-d50f-11e3-900e-6b7c5798f74b.png)