fix overflow in sidebar. 

When and image is displayed the working-set-header and project-dropdown-toggle bleed into the image holder, when the sidebar is narrow. This change fixes that.
![sidebar-bleeds-into-image](https://f.cloud.github.com/assets/887904/1411569/97ca4b70-3dba-11e3-935b-16fe044aaa5d.png)

Thanks @larz0 for finding this and bringing it to my attention.

This change also improves the sidebar look when the working set title and project dropdown are truncated by adding an ellipsis.