add support for purging config files

the same as:
https://github.com/puppetlabs/puppetlabs-glance/pull/68

lib/puppet/provider/cinder_api_paste_ini/ini_setting.rb

@@ -15,8 +15,13 @@ Puppet::Type.type(:cinder_api_paste_ini).provide(
     '='
   end
 
-  def file_path
+  def self.file_path
     '/etc/cinder/api-paste.ini'
   end
 
+  # added for backwards compatibility with older versions of inifile
+  def file_path
+    self.class.file_path
+  end
+
 end

lib/puppet/provider/cinder_config/ini_setting.rb

@@ -15,8 +15,13 @@ Puppet::Type.type(:cinder_config).provide(
     '='
   end
 
-  def file_path
+  def self.file_path
     '/etc/cinder/cinder.conf'
   end
 
+  # added for backwards compatibility with older versions of inifile
+  def file_path
+    self.class.file_path
+  end
+
 end