add checkfilepolicy flag to loading context

Hi Marek,
this change I've made corrects the problem I described in the forum :
http://panozona.com/wiki/Special:AWCforum/st/id225/django-saladoplayer_%3A_saladoplay....html
SaladoPlayer does not check crossdomain.xml file if this flag is not set to true. This file must be present at the root of the domain so that the flash script can read its content.
Cheers,
Franck

http://support.brightcove.com/en/video-cloud/docs/cross-domain-security-flash
http://www.adobe.com/devnet/articles/crossdomain_policy_file_spec.html