Editable SEO fields

![fronst-tool](https://cloud.githubusercontent.com/assets/1147913/2888648/f779ceba-d50e-11e3-8504-837c4bb7fb0f.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)