Bump version to 2.8.5

Change-Id: I177ccfd2a3db387822085602dfc66267703c0a48
Release notes for Gerrit 2.8.5

Change-Id: I87b951065a8331e635f042ece7266c9e859516be
Add more information about Bouncycastle upgrade in 2.8.5 release notes

Since Bouncycastle is not included in the Gerrit distribution, the site
init must be run in order to get the updated libraries.

Mention this in the release notes.

Change-Id: Ia42239cbf4cbe9328ece1670e15bbd272ec2875e