variables should not be substituted in message

Using $priority meant it would be substituted with the value of the
parameter when it should be shown as static text.
validations for nginx::init
validations for nginx::resource::location
validations for nginx::resource::vhost
validations for nginx::resource::mailhost
validations for nginx::resource::upstream
warn on inclusion of nginx::config
warn on inclusion of nginx::package
warn on inclusion of nginx::params
warn on inclusion of nginx::service
warn on inclusion of nginx::package::debian
warn on inclusion of nginx::package::redhat
warn on inclusion of nginx::package::suse
Merge pull request #227 from 3flex/validations

Validations for all parameters in the public classes