Fix improper usage of Fileutils#rm_f in ifconfig provider

This also corrects the test that was commented out for some reason

chef/lib/chef/provider/ifconfig.rb

@@ -199,7 +199,7 @@ class Chef
           ifcfg_file = "/etc/sysconfig/network-scripts/ifcfg-#{@new_resource.device}"
           if ::File.exist?(ifcfg_file)
             converge_by ("delete the #{ifcfg_file}") do
-              FileUtils.rm_f(ifcfg_file, :verbose => false, :force => true)
+              FileUtils.rm_f(ifcfg_file, :verbose => false)
             end
           end
         when "debian","ubuntu"

chef/spec/unit/provider/ifconfig_spec.rb

@@ -205,8 +205,8 @@ describe Chef::Provider::Ifconfig do
       @provider.stub!(:run_command)
       config_filename =  "/etc/sysconfig/network-scripts/ifcfg-#{@new_resource.device}"
       File.should_receive(:exist?).with(config_filename).and_return(true)
-      FileUtils.should_receive(:rm_f)#.with(config_filename, :verbose => false, :force => true)
-      
+      FileUtils.should_receive(:rm_f).with(config_filename, :verbose => false)
+
       @provider.run_action(:delete)
     end
   end