Style guideline fix for README example's mode

puppet-lint reports that 644 should be '0644', per http://puppet-lint.com/checks/file_mode/
Merge pull request #40 from floatingatoll/patch-1

Style guideline fix for README example's mode
Adding more helpful message for 'pluginsync = true'.
Merge pull request #41 from raphaabreu/master

Changing messages related to pluginsync to indicate where this setting should be put.