Don't print the page title heading when there isn't a title.

Really small change but we noticed a blank heading being inserted on the default home-page (which is likely to be the case for the home page).

With empty header
![with header](https://f.cloud.github.com/assets/96776/2176754/14139abc-95de-11e3-97ee-952628e60be2.png)

Without empty header
![without header](https://f.cloud.github.com/assets/96776/2176756/257dd934-95de-11e3-8208-12b8bde4617d.png)