JIRA Issue pages should fail nicely if connection broken

If the JIRA Server is down, The JiraIssueManager blows up badly, causing all sorts of horrible things to happen. Like not reporting that issues even exist, Stacktraces on the UI etc, saying issues exist then showing a blank screen.

It should not propogate the error to the user, the user should still see the issue keys and a "could not fetch details" message.

This was also plaguing when writing a plugin that used the issue manager.