Allow flavor ID override in request calc methods

If a service request includes a flavor override it needs to be passed to
the template *_for_request calculation methods.

app/models/manageiq/providers/cloud_manager/template.rb

@@ -155,13 +155,15 @@ def self.display_name(number = 1)
     n_('Image', 'Images', number)
   end
 
-  def memory_for_request(request)
-    flavor_obj = Flavor.find(request.get_option(:instance_type))
+  def memory_for_request(request, flavor_id = nil)
+    flavor_id ||= request.get_option(:instance_type)
+    flavor_obj = Flavor.find(flavor_id)
     flavor_obj.try(:memory)
   end
 
-  def number_of_cpus_for_request(request)
-    flavor_obj = Flavor.find(request.get_option(:instance_type))
+  def number_of_cpus_for_request(request, flavor_id = nil)
+    flavor_id ||= request.get_option(:instance_type)
+    flavor_obj = Flavor.find(flavor_id)
     flavor_obj.try(:cpus)
   end