FR: Show links to gerrits

[alanvgreen]

It would be convenient to use gerrit-monitor as a shortcut to gerrit. This is would be useful since there are occasions when I want to visit gerrit even when I don't have a change requiring attention.

For instance, if I am monitoring https://chromium-review.googlesource.com, then there could be a link to https://chromium-review.googlesource.com in the gerrit-monitor drop down.