Annex the Admin Toolbox, re-style, add username, simplify

Fixes #853 and improves Admin Toolbox in general.

We now include embedded CSS with the toolbox function, and use unique IDs to scope it and ensure it doesn't conflict with anything. The IDs have been changed, so old themes with toolbox styles should not have a problem.

This also removes the old Admin Toolbox styles from included themes.

Before:

![screenshot 2014-09-01 16 40 45](https://cloud.githubusercontent.com/assets/89588/4112427/7b2aae84-3228-11e4-951f-654aed8c5546.png)

After:

![screenshot 2014-09-01 18 37 09](https://cloud.githubusercontent.com/assets/89588/4112430/8e75c500-3228-11e4-9c09-c962eed06022.png)
![screenshot 2014-09-01 18 37 19](https://cloud.githubusercontent.com/assets/89588/4112432/96741784-3228-11e4-9dd1-cac0c3f0f322.png)