Barnum (pt) download link is incorrect for war deployment

[gitblit]

Originally reported on Google Code with ID 602

What steps will reproduce the problem?
1. Browse to a ticket created for a project
2. Select the commits tab
3. Click the "about Barnum" link
4. From the modal info box, click the download link

When deployed as a WAR, the Barnum download link doesn't work because it doesn't include
accomdation for adding the context path. It should be, for example, /gitblit/pt instead
of a literal /pt, which generates a 404.

Reported by mrjoelseph on 2015-07-01 23:15:38

[flaix]

Sounds related to #855, #902.