Fix formatting of 'upload files' label on bug_report_page.

Before the change:
![screen shot 2014-01-18 at 6 34 12 pm](https://f.cloud.github.com/assets/6446/1948797/725876f6-80b2-11e3-9a1f-a7c993019f90.png)

After the change:
![screen shot 2014-01-18 at 6 33 51 pm](https://f.cloud.github.com/assets/6446/1948798/7709ee00-80b2-11e3-96fd-34da40664590.png)