[JIRA] (OVIRT-1777) Upgrade Gerrit to 2.15

Upgrade Gerrit to 2.15 ---------------------- Key: OVIRT-1777 URL: https://ovirt-jira.atlassian.net/browse/OVIRT-1777 Project: oVirt - virtualization made easy Issue Type: Task Reporter: Evgheni Dereveanchin Assignee: Evgheni Dereveanchin Gerrit 2.15 is going to be released soon (RC2 is out now). We should upgrade Staging once the release happen and test out the new [NoteDB backend|https://gerrit-review.googlesource.com/Documentation/note-db.html] to see how it performs. Before upgrading we need to get the latest 2.14 version installed on both Staging and Prod.