Persist TestrunMessages and store timestamp

So far, the Testrun messages are in addition to the Tesstrun.output column

app/models/application_record.rb

@@ -8,7 +8,8 @@ class ApplicationRecord < ActiveRecord::Base
   def strip_strings
     # trim whitespace from beginning and end of string attributes
     # except for the `content` of CodeOcean::Files
-    attribute_names.without('content').each do |name|
+    # and except the `log` of TestrunMessages or the `output` of Testruns
+    attribute_names.without('content', 'log', 'output').each do |name|
       if send(name.to_sym).respond_to?(:strip)
         send("#{name}=".to_sym, send(name).strip)
       end