Remove usage of custom os_package_type fact

Currently we support usage of distro packages only, and this custom
fact can be simply replaced by the default fact.

Change-Id: I7b95079b1ec59da3b4b9d1cd149019acaa80ea7b

manifests/init.pp

@@ -695,7 +695,7 @@ removed in a future realse. Use keystone::db::database_max_overflow instead')
 
       # Note: Debian uses uwsgi if using keystone service, which isn't deprecated
       # and therefore, no warning should be displayed.
-      if $service_name == $::keystone::params::service_name and $::os_package_type != 'debian'{
+      if $service_name == $::keystone::params::service_name and $::operatingsystem != 'Debian'{
         warning("Keystone under Eventlet has been deprecated during the Kilo cycle. \
 Support for deploying under eventlet will be dropped as of the M-release of OpenStack.")
       }

manifests/wsgi/uwsgi.pp

@@ -29,7 +29,7 @@ class keystone::wsgi::uwsgi (
 
   include keystone::deps
 
-  if $::os_package_type != 'debian'{
+  if $::operatingsystem != 'Debian'{
     warning('This class is only valid for Debian, as other operating systems are not using uwsgi by default.')
   }