Modified the template to truncate the page's menu_title.

The reason being that after the title reaches a certain point the UI breaks.
By default I chose to truncate after 100 characters, since it's a pretty reasonable amount.


![cms-admin-bug](https://f.cloud.github.com/assets/994951/48804/5909302c-5922-11e2-82f8-5f2e898afe97.png)