Don't abort when database.yml is not present.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11202 e93f8b46-1217-0410-a6f0-8f06a7374b81
database.yml should be configured first.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11203 e93f8b46-1217-0410-a6f0-8f06a7374b81
Set ruby1.9 as default for the database configuration example.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@11204 e93f8b46-1217-0410-a6f0-8f06a7374b81