Updates for 2.5.3 release.

git-svn-id: http://svn.redmine.org/redmine/branches/2.5-stable@13470 e93f8b46-1217-0410-a6f0-8f06a7374b81
Merge remote-tracking branch 'upstream/2.5-stable' into ro-2-5
bundle update
upgrade 2.1.4
use unicorn instead of passenger