Fix the installed Ruby version to 1.9.3-p392, for Redmine.

After introducing ruby_setup provider,
it installs Ruby version other than 1.9.3-p392.

Before, Redmine is providing its service under Ruby 1.9.3-p392.
So, Fix the installed Ruby version to 1.9.3-p392.

This commit fixes #215.
Merge branch 'id/215' into dev