Creating a review hangs when automatically linking JIRA issues to reviews if JIRA isn't responsive.

Steps to reproduce:

1. Integrate your JIRA server with Crucible so that reviews will be autolinked to JIRA issues
2. Commit a changeset to your repository referencing a jira issue e.g. TST-3
3. Suspend the JIRA instance using something like kill -s SIGSTOP <pid> to simulate a non responsive instance
4. Try to create a review from the changeset referencing TST-3. If the JIRA issue is not already in the cache, Crucible will make a remote call to JIRA to get the issue details. Since we suspended JIRA (or if JIRA is actually not responding) Crucible will just hang and the spinning wheel throbber will never go away.
   
   
   

We should put some sort of timeout after which the issue linking fails with a message saying JIRA was not responding and the auto-linking failed.