Change container_quota_items float columns to decimals

Fixes ManageIQ/manageiq-providers-kubernetes#208
Kubernetes quotas are mostly integers but cpu-related quotas are
in "millicores", multiples of 0.001.
With decimal columns, we'll be able to round-trip quotas exactly to DB
and back to Ruby, so refresh can determine whether they changed or not.

https://bugzilla.redhat.com/show_bug.cgi?id=1504560

db/migrate/20180110110113_change_container_quota_items_to_decimals.rb

@@ -0,0 +1,13 @@
+class ChangeContainerQuotaItemsToDecimals < ActiveRecord::Migration[5.0]
+  def up
+    %i(quota_desired quota_enforced quota_observed).each do |column|
+      change_column :container_quota_items, column, :decimal, :scale => 3, :precision => 30
+    end
+  end
+
+  def down
+    %i(quota_desired quota_enforced quota_observed).each do |column|
+      change_column :container_quota_items, column, :float
+    end
+  end
+end