Fix installation when MySQL listens on public port

If the mysql server's bind_address isn't set to 127.0.0.1 through a role, then
it's not possible to set up Gerrit, as the root user is not allowed to connect.

Overriding the bind_address solves this issue. A more clever idea is welcome..

This reverts commit 5aa047430c6b2c3ff47a2747af5f0515d003430b.
Update Download URL and set Gerrit version to 2.6.1