Quickly expand or collapse parts in a guide or programme

* Use a single toggle all link to collapse or expand all parts to a guide or programme
* Move a part's slug to beneath the title, rather than being hidden beneath the body field
* Style add and remove part actions as buttons

![screen shot 2014-10-14 at 13 48 14](https://cloud.githubusercontent.com/assets/319055/4629100/72d1a348-53a0-11e4-9977-3e05dc47dfe6.png)

![screen shot 2014-10-14 at 13 48 08](https://cloud.githubusercontent.com/assets/319055/4629099/72cebdb8-53a0-11e4-85a9-02d2124a6d2b.png)