Upgrade to Rails 2.3.15.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/branches/1.4-stable@11148 e93f8b46-1217-0410-a6f0-8f06a7374b81
Changes for 1.4.6 release.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/branches/1.4-stable@11149 e93f8b46-1217-0410-a6f0-8f06a7374b81
Removed Rails patch.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/branches/1.4-stable@11154 e93f8b46-1217-0410-a6f0-8f06a7374b81