Fix invalid conversion host resource type

Fix an invalid polymorphic resource_type from
ManageIQ#281 which resulted in
the type being "AddConversionHostIdToMiqRequestTasks::Host" instead of
"Host".

db/migrate/20181002192054_fix_conversion_host_resource_type.rb

@@ -0,0 +1,14 @@
+class FixConversionHostResourceType < ActiveRecord::Migration[5.0]
+  class ConversionHost < ActiveRecord::Base
+    self.inheritance_column = :_type_disabled
+    include ActiveRecord::IdRegions
+  end
+
+  def up
+    say_with_time("Converting invalid resource_type to Host") do
+      ConversionHost.in_my_region
+        .where(:resource_type => "AddConversionHostIdToMiqRequestTasks::Host")
+        .update_all(:resource_type => "Host")
+    end
+  end
+end