Add link hover effect, enlarge page link size

This pull request ensures that a hover effect is present, when links in the top nav-bar are selected, so that page transitioning is more seamless. This also enhances page accessibility.

The effects look something like the following:
![keen](https://cloud.githubusercontent.com/assets/3946887/5311667/107ee6b4-7c96-11e4-8d3d-6baf6398da06.png)

The clickable area of the "return" links on both the examples and layouts page have been enlarged, so that users may now click the link text in order to return to the previous page.

Thanks for creating these dashboard templates!
psgs :palm_tree: