Issue

• While upgrading CFME from 3.2 to 4.1, 'rake db:migrate' command fails.

• Command bin/rake db:migrate was aborted with following error:

  -- Converting BinaryBlob report results to a serialized hash
  rake aborted!
  StandardError: An error has occurred, this and all later migrations canceled:
  
  unexpected format of report attribute encountered, '""'/var/www/miq/vmdb/db/migrate/20150625220141_fix_serialized_reports_for_rails_four.rb:14:in `serialize_report_to_hash'
  /var/www/miq/vmdb/db/migrate/20150625220141_fix_serialized_reports_for_rails_four.rb:138:in `block (2 levels) in up'
  /opt/rh/cfme-gemset/gems/activerecord-5.0.0.1/lib/active_record/relation/batches.rb:59:in `block (2 levels) in find_each'
  /opt/rh/cfme-gemset/gems/activerecord-5.0.0.1/lib/active_record/relation/batches.rb:59:in `each'
  /opt/rh/cfme-gemset/gems/activerecord-5.0.0.1/lib/active_record/relation/batches.rb:59:in `block in find_each'
  /opt/rh/cfme-gemset/gems/activerecord-5.0.0.1/lib/active_record/relation/batches.rb:121:in `block in find_in_batches'
  /opt/rh/cfme-gemset/gems/activerecord-5.0.0.1/lib/active_record/relation/batches.rb:214:in `block in in_batches'"