Update Guice version to 4.0-beta5

Beta 5 releases the fix to Cookie mutability bug [1], so that we can
switch again to Central repository and don't need custom Guice
guice-servlet build.

[1] http://code.google.com/p/google-guice/issues/detail?id=806

Change-Id: Ia766f3d9163afdae06ea7c702824909a8349b98e
Initial release notes for Gerrit 2.10

Change-Id: Iccaf7d4ea66eff290967c41ee70348a4dfc4511b