slapos_subscription_request: Subscription Requests can set prices

The price is defined on the subscription request and copied into the Open Order later, for periodical payments.

master/bt5/slapos_subscription_request/PortalTypePropertySheetTemplateItem/property_sheet_list.xml

@@ -12,6 +12,7 @@
   <item>CredentialRequest</item>
   <item>HostingSubscription</item>
   <item>Person</item>
+  <item>Price</item>
   <item>Reference</item>
   <item>SlapOSAccountingHostingSubscriptionConstraint</item>
   <item>SlaposHostingSubscriptionConstraint</item>

master/bt5/slapos_subscription_request/bt/template_portal_type_property_sheet_list

@@ -8,6 +8,7 @@ Subscription Request | Amount
 Subscription Request | CredentialRequest
 Subscription Request | HostingSubscription
 Subscription Request | Person
+Subscription Request | Price
 Subscription Request | Reference
 Subscription Request | SlapOSAccountingHostingSubscriptionConstraint
 Subscription Request | SlaposHostingSubscriptionConstraint