Changed postrotate option to accept array value

This allows for multi-line postrotate values when a rotation requires
multiple commands to be executed upon completion.
Add .ruby-version to gitignore
Merge branch 'master' of https://github.com/gudlyf/puppet-logrotate into gudlyf-master
Update documentation to reflect the array of postrotate commands
Add test case for array of postrotate commands
support postrotate as both an array and a string