Feature/performance caching

Hi Dan;

Removed context_id from collection JSON response as well as filter out relationship property as well as AssociationProxy for read permission checks.

Ran run_behave and run_unittests and there were no errors related to context_id. run_unittest have other errors such as DB errors. 

Also verify the functionality of Read permissions by mapping a private program to a existing Market resource  using non-admin/admin manually and also manually clear memcache and tried again. 

Also ran concurrent and load tests successfully.

Regards
Mouli